CDK4 and breast carcinoma: The oncogene, CCND2, is overexpressed in breast cancer,26 and it is characterized as the regulator of G1 to S-phase transition during the cell cycle.27,28 The critical function of CCND2 is attributed to assemble a complex with CDK4/CDK6, motivate the phosphorylation of Rb protein, releasing the E2F transcription factor, and, subsequently, activating the genes transcription involved in the progression of G1 to S phase.26,27 As shown in Figure 3, compared with the control groups, there was a noticeable decrement in the mRNA and protein expression of CCND2 in SFN-treated cells.