mRNA samples from two human-derived cell lines (HepG2 hepatocellular carcinoma and HEK293T human embryonic kidney) and from human brain tissue were reverse-transcribed into cDNA, and the presence of SCD5A and B TVs was tested by RT-PCR using primers specific for the common exon 2 and E5A and E4B, respectively, (Figure 1D) and a GAPDH-specific reaction as a control. Here, GAPDH is linked to hepatocellular carcinoma.