NPR2 and colorectal cancer: Following administration of 1×106 cells of HTC-116 cells (lenti-luc-transfected colorectal cancer cell) into the male athymic nude mice (6–8 weeks old), NPR-2-siRNA/liposomal complexes (NPR-2-siRNA-DOPC) and siRNA-DOPC (without NPR-2) as a negative control were given intraperitoneally at a dose of 5 μg of siRNA on every 5 days.