SESN1 and skin basal cell carcinoma: The absence of c-MYC, Sestrin-1, and SRPX2 regular transcriptional activity, together with the retention of specific introns in their respective transcripts (Figure 1, Figure 3 and Figure 5), seem to comprise a novel, reliable and powerful composite molecular signature for the genotypic distinction of human melanoma from BCC and SCC non-melanoma tumors.