Poly(C)-binding protein 4 (PCBP4), also known as MCG10, is an RBP belonging to the poly(C)-binding protein family and a target of p53 tumor suppressor. PCBP4 plays a role in the cell cycle and is implicated in lung tumor suppression. Ectopic expression of PCBP4 induces cell-cycle arrest in G₂ and apoptosis. PCBP4 regulates both basal and stress-induced p21 expression through binding p21 3'-UTR and modulating p21 mRNA stability. alpha CP-4 is an RNA-binding protein coded by PCBP4, a gene mapped to 3p21, a commonly deleted region in lung cancer. PCBP4 plays important role in the induction of cisplatin resistance in human maxillary cancers. PCBP4 is a novel molecular target for the therapy of head and neck cancers, especially cisplatin-resistant cancers.