GAPDH and skin basal cell carcinoma: To validate and extend our findings from the RNA-seq analysis, we conducted qPCR on our 10 candidate RGs in addition to the three commonly used skin RGs ACTB, GAPDH, and HPRT1 on samples derived from a diversity of skin conditions within the spectrum of NMSC (SCC and precursors and BCC) (refer to Table 1 for list of gene primers).