Other effects of melatonin on viral infections have been reported to include the anti-tumor property on human papillomavirus (HPV) infection, as evidenced by the direct reduction in proliferation, migration, adhesion and viability of TC-1 tumor cell lines; this investigation used a combination of melatonin and an indoleamine 2,3-dioxygenase inhibitor [105]. The gene discussed is IDO2; the disease is neoplasm.