VIP and hepatocellular carcinoma: To investigate whether VIP can elicit anti-tumor effects in vivo, we established HCC xenograft mouse models by subcutaneously implanting VIPR1 overexpressing HCCLM3 cells (HCCLM3-VIPR1) or vector transduced with HCCLM3 cells (HCCLM3-Vector) in the back of nude mice.