CD4 and neoplasm: On the contrary to HIV-1 RT, expression of rtTERT does not enhance tumorigenic properties of cancer cells (4T1luc2), but instead reduces their capacity to form tumors and metastasis, induces CD8+ T cell immune response to epitopes within rtTERT associated with restriction of tumor growth, and suppresses CD4+ T cell response to an autoepitope of TERT associated with tumor growth and metastatic activity.