In 1984, genetic scientists led by Philip Leder created the first genetically engineered mouse model of cancer, nicknamed the ‘Oncomouse.’

The team had successively developed breeding female MMTV-Myc transgenic mice, monitoring them as they aged. Their patience and persistence were rewarded: Mammary tumors began to appear after the second or third pregnancy in the female founders of two of the 13 lines and, in turn, in their female progeny.

The successful development of the MMTV-Myc mouse model of breast cancer was enabled by the complementary expertise and knowledge of the Leder laboratory in molecular biology and of Tim Stewart in transgenic mouse technology.