CDKN1B and cancer: We then specifically focused on whether PCBP1 modulates p27 expression with three reasons: first, cell cycle plays a crucial role in tumorigenesis and cancer progression; second, p27 is one of the most important guardians in cell cycle; third, PCBP1 has been confirmed to interact with p21 mRNA, it is reasonable to inquire the existence of an coordinated interaction between PCBP1 and p27 mRNA to modulate cell cycle.