Press Release

Cellectis S.A. announces the registration of its Document de Base with the AMF in the context of the Company's contemplated initial public offering on the Alternext market of Euronext Paris.

Romainville, France - December the 26^th, 2006 - Cellectis S.A., a biotechnology company specialized in genome engineering and developing a new range of products for the custom rewriting of DNA sequences for the research, healthcare and industrial fields, announced the registration of its Document de Base with the "Autorité des Marchés Financiers" (AMF) under number I.06 - 198 on December 22^nd, 2006. This is a key step towards the company's contemplated initial public offering on the Alternext market of Euronext, Paris.

About Cellectis S.A.

Cellectis S.A. is a biotech company developing innovative, proprietary technologies for genome engineering: a new class of "molecular scissors" - Meganuclease^TM enzymes - capable of recognizing, binding and cutting DNA with extremely high specificity. The company is developing and commercializing Meganuclease Recombination Systems (MRSs) which combine these molecular scissors with a DNA matrix for targeting and modifying a gene of interest in vivo (and without affecting the rest of the genome) via the action of the cell's natural maintenance and repair system. By developing this first-in-class technology on the industrial scale, Cellectis has opened the way to rational genome engineering, which seeks to accurately and reliability insert, modify, modulate or correct genes in any living organism - without the addition of foreign genes, which are often imprecise and poorly tolerated. Cellectis is currently developing 8 MRSs.

Founded in 2000 by André Choulika and David Sourdive, Cellectis is a spin-off from Institut Pasteur in Paris, which has granted the company exclusive rights to a portfolio of patents. The company holds a portfolio of 27 granted patents and 69 pending applications. Since its creation, Cellectis has raised 17.5 million euros in two rounds (in 2000 and 2002) to support its R&D and commercial development. The company's principal shareholders are AGF Private Equity, BankInvest Biomedical Venture, Edmond de Rothschild Investment Partners, Kaminvest Holding and Odyssée Venture. To date, Cellectis has signed 45 collaboration agreements and alliances worldwide with pharma companies (including AstraZeneca, Merck & Co., Wyeth and Shire), agrochemical groups (including Bayer, DuPont and BASF) and biotech companies (including Genentech, Regeneron and Lexicon Genetics) worldwide. Cellectis' corporate headquarters are located on the Biocitech biopark at Romainville near Paris. It currently has 40 staff, including 16 PhDs.
For more information on Cellectis, visit our web site: www.cellectis.com

Availability of the document de base

The document de base registered on December 22nd, 2006 under number I.06 - 198 is available, free of charge and on demand, from Cellectis S.A. at 102, route de Noisy, 93235 Romainville, France, and on the websites of the "Autorité des Marchés Financiers" (www.amf-france.org) and Cellectis (www.cellectis.com).

Risk factors

Cellectis draws the attention of the public to the section entitled "Risk Factors" in its document de base registered with the "Autorité des Marchés Financiers". These risk factors are discussed in detail in Chapter 4 of the document de base.

This press release, and the information contained herein, do not constitute an offer to sell or a solicitation of an offer to buy or subscribe for shares in Cellectis in any country. No offer to sell shares in Cellectis has been made, nor will be made, prior to the official approval by the Autorité des marchés financiers (AMF) of a prospectus that will include the document de base, which is the subject of this press release, a note d¿opération and a summary, which will be submitted to the AMF at a future date.

Shares in Cellectis may not be sold in the United States of America absent registration or an exemption from registration under the U.S. Securities Act of 1933, as amended. There will be no registration of all or part of the offering referred to in this press release in the United States of America nor any public offering of Cellectis in the United States of America. This press release may not be distributed, in particular, either directly or indirectly, in the United States of America and does not constitute an offer to sell securities in the United States of America.

Copyright © Cellectis 2006. All rights reserved.