CDK4 and cancer: They synthesized different pyrido pyrimidine derivatives and checked their in vitro activity against human cancer lines (breast MCF-7, lungs A-549, and prostate PC-3),103 Cell cycle analysis,104 Apoptosis assay,105 Caspase activation assay,106 RT-PCR for (Bax, Bcl2,p53, and CDK4/6), and compound 116 showed excellent activity against Caspase-3 (Table 5).