Crossing of the nm23-h1/nm23-h2 knockout in hemizygous-null form ([m1m2]+/−) to a transgenic mouse strain (hepatocyte growth factor/scatter factor-overexpressing, or HGF+ strain) vulnerable to poorly-metastatic, UVR-induced melanomas resulted in UVR-induced melanomas with high metastatic potential. Here, HGF is linked to melanoma.