ERVW-1 and squamous cell carcinoma: Analysis of the expression of HERV-K (HML-2) gag, pol, and env in lung cancers showed that the transcriptional levels of gag, pol, and env mRNA were significantly higher in SCLC, adenocarcinoma, squamous cell carcinoma, and large cell carcinoma than in healthy controls (Figures 1D–F).