CDKN2A and skin squamous cell carcinoma: The genetic landscape of cutaneous SCC (CSCC) includes the alterations of tumor-suppressor genes such as TP53, CDKN2A, NOTCH1, NOTHC2, and p16; epigenetic regulators including ARID2, CREBBP, KMTC2, KMT2A, SETD2, and TET2; and mutations in DNA repair pathways and in TGF-β receptors.