Paris, Lyon, France, April, the 16^th, 2003

Cellectis grants Nucleis a non-exclusive commercial license under the patent family covering the use of the homologous recombination in mice

Paris, Lyon; France - April 16, 2003 - Cellectis, the rational genome engineering company, announced today that the company has granted Nucleis a non-exclusive commercial license, under the patent family relating to a process for the specific replacement or insertion of a gene in the receiver genome by homologous recombination in mice.
Through this license agreement, Cellectis grants Nucleis the right to use its patented technologies for the engineering of mice cell lines and/or the generation of mice as animal models. Financial terms and conditions of the agreement were not disclosed.

Homologous recombination, which relies on natural cellular DNA maintenance and repair mechanisms present in all living organisms, is the technological basis of rational genome engineering, Cellectis' expertise.
Among other applications, homologous recombination is systematically used for gene "knock-outs" and "knock-ins".

"Homologous recombination licensed to Nucleis is of most robust technologies since a decade for in vivo mammalian trangenesis, and remain at the cutting edge today", commented Isabelle Bressac, Vice-president Business Development of Cellectis. "Moreover, our Homologous Recombination patents family is very broad and strong in Europe, Japan and the USA", she added.

Biotechnological company created in 2002 in Lyon (France), NUCLEIS SA is specialized in custom made mice transgenesis. Nucleis is employing a team of 14 scientists and technicians with a strong expertise in mice transgenesis. Nucleis animal house is integrated in a brand new A2 and SPF transgenesis center which responds totally to the most drastic sanitary requirements.
Nucleis' R&D is focused on programs aiming at optimizing the creation of specific transgenic lines through the improvement of time, predictability and selection. Nucleis is conducting these R&D programs thanks to its own expertise and in partnership with qualified research teams such as College de France, Pasteur Institute, Curie Institute, (Paris), McGill University (Montreal) and Lyon 1 Claude Bernard University. The main R&D program was just attributed the 2003 GenHomme Label.
For more information, please visit Nucleis' website at http://www.nucleis.com.

CELLECTIS SA was founded in 1999, as a spin-off from the Institut Pasteur. It is the first company to apply the Meganuclease Recombination System approach to in vivo genome engineering. Cellectis is focused on the research and development of novel Meganucleases for genome intervention and provides tools for in vivo site directed recombination.
The company is developing Meganucleases that can target a unique DNA break in vivo, as a fundamentally enabling technology for commercial applications as human therapeutics for genetic and infectious diseases, pharmaceutical discovery, agriculture and industrial biotechnology.
Cellectis' team today consists of 35 people including 14 PhDs and the total invested capital since the company's inception is approximately EUR 20 million.
As of today, Cellectis has entered into more than 10 deals on Genome Engineering technologies.
For more information, please visit Cellectis' web site at http://www.cellectis.com.