TNF and melanoma: In engineered melanoma cells (A375hTNFa, M4BeuhTNFa) and colorectal carcinoma cells (HT29hTNFa, HCT116hTNFa), stable retroviral transduction elevated the mRNA expression of TNFα transgene up to 130.000x (engineered cells with approx. Cq 14–16 vs. parental cells with Cq 30–33; RTqPCR, Fig. 1a).