Apigenin mediated alterations in signaling pathways observed in colorectal cell lines HCT-15 and HT-29. (a) Western blot analysis of pRb (Ser780), cyclin E, cyclin D1, p16, p53, p21WAF-1 proteins in colorectal cancer cells untreated/treated with senescence inductive dose of apigenin. (b and c) Densitometric analysis of the protein bands obtained by western blot in apigenin treated/untreated HCT-15 and HT-29 cells respectively. (d) Schematic summary of p16INK4a-Rb and p53–p21 signaling pathway alterations in colorectal cells occurring following apigenin treatment.