ERV3-1 and neoplasm of testis: One study compared the mRNA expression of HERVs in tumors to adjacent normal tissues and found high levels of HERV-K (HML-2) expression in testis tumor tissues, HERV-R (ERV3-1) in liver and lung tumor tissues, HERV-H in liver, lung, and testis tumor tissues, and HERV-P in colon and liver tumor tissues [16].