CASP3 and breast cancer: We followed a prospective cohort consisting of virgin female Casp3 knockout/PyMT positive (Casp3KO;Pymt, n = 20) mice and of Casp3 wild type/PyMT positive (Casp3WT;Pymt, n = 18) female littermate control mice to determine the impact of caspase-3 deficiency on primary mammary tumor development.