SRPX2 and melanoma: Notably, the absence of retained introns in the MCT1 (313 bp), XIAP (225 bp), and GAPDH (189 bp) (and also GMFG (237 bp); Figure S1F) RT-sqPCR melanoma-specific products (Figure 6) (whose respective forward and reverse primers were designed to anneal within different exon sequences (Table S1)) serves as strong internal control/marker for the purity of our RNA/cDNA preparations, and demonstrates the RNA- and non-DNA-dependent origin of the retained introns in the c-MYC, MCT4, Sestrin-1, and SRPX2 human melanoma RT-sqPCR fragments (Figure 1, Figure 2 and Figure 3 and Figure 5).