The response to anti-PD-1 and anti-CTLA-4 ICT in wild-type (WT) and CXCR3KO mice has been evaluated using the Ret transgenic mouse model, a skin malignant melanoma model that is characterized by the overexpression of the human Ret transgene in melanin-expressing cells (33). The gene discussed is CTLA4; the disease is cutaneous melanoma.