Mark S. Ptashne, PhD, is an Emeritus Member of the Sloan Kettering Institute at Memorial Sloan Kettering Cancer Center (MSK).

Over the course of five decades, Dr. Ptashne’s work defined core principles of transcriptional regulation. His work in lambda was focused on the understanding the mechanisms underlying the switch from lytic to lysogenic lifecycle, and it was in that context that he first articulated the concept that a universal feature of genetic regulation was the modular nature of the proteins involved: sequence specific DNA binding domains form one module, while a second module serves to recruit effector proteins. Dr. Ptashne, who held the Ludwig Chair of Molecular Biology at MSK, has been a major figure in the field of molecular biology for more than 50 years.