To examine this further we collected additional breast cancer (MDA-MB-453, T47D, ZR-75-1, and MCF7), lung cancer (A549, H1975, H358, H3122, Calu-1) and glioma (U87-MG, U251, and DBTRG-05MG) cell lines in which MDM2 was not amplified and treated these with PD0332991 to look at the hallmark characteristics of senescence. The gene discussed is MDM2; the disease is breast cancer.