Press Release

Cellectis S.A. announces its attendance at two high-profile conventions:
The BIO International Convention, Boston, May 6^th-9^th 2007
BioEquity Europe, Glasgow, May 21^st-22^nd 2007.

Romainville, France - May the 3^rd, 2007 - Cellectis S.A. (Alternext: ALCLS), the rational genome engineering company developing a new range of custom DNA rewriting products for the research, healthcare and industrial sectors, today announced that it will attend the BIO International Convention in Boston (May 6^th-9^th 2007) and BioEquity Europe in Glasgow (May 21^st-22^nd 2007).

The BIO International Convention is a global event that brings together business leaders, entrepreneurs, academics and investors with the aim of forging industrial and academic alliances and learning about the latest innovations and future trends in biotech and its fields of application: healthcare, agrifood, industry and the environment.
Cellectis will be represented at BIO Boston by André Choulika (the company's founder and CEO) and David Sourdive (Vice President Corporate Development). The latter will also give a presentation entitled "INGENIS: the concept of Meganuclease-mediated genome surgery for new therapeutic approaches" at the "Fast Track R&D Partnering with France" BIO satellite event on May 6^th (www.anatome.fr/FTRD/program.html).

BioEquity Europe is a high-profile annual convention for European life science companies and investors. Cellectis will be represented by André Choulika (the company's founder and CEO) and Marc le Bozec (CFO). Mr. Choulika will be presenting Cellectis and its corporate news & development strategy.

Cellectis will also be attending 'BioFinance' at the Wellcome Collection Conference Centre, London, on June 18^th 2007. André Choulika will participate in a Round Table at 2pm entitled "Choosing your public market strategy: perspectives from alternative European exchanges".

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™ 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 technology on the industrial scale for the first time ever, Cellectis has opened up the way to rational genome engineering, which aims at reliably and accurately inserting, modifying, modulating or correcting genes in vivo in any living organism, without the often imprecise and poorly tolerated addition of foreign DNA. Cellectis now holds a portfolio of 8 MRSs in development, of which 5 have a therapeutic focus.
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). Cellectis' corporate headquarters are located on the Biocitech biopark at Romainville near Paris. It currently has 45 staff, including 17 PhDs. Cellectis is listed on the Alternext market of Euronext (ALCLS). For more information on Cellectis, visit our web site: www.cellectis.com