By contrast, none of the groups treated with VIS-PDT had detectable S100 or Ki-67 staining in the non-pigmented tumors (p < 0.0001 compared to untreated controls), indicating that targeting the vasculature was more effective than targeting the tumor cells directly; this is consistent with the fact that melanomas have a rich vascular network [38]. Here, MKI67 is linked to melanoma.