A direct stimulatory effect on proliferation has been demonstrated in different models, for instance downregulation of HO-1 by means of siRNA was associated with a significant inhibition of pancreatic tumor cells growth [26], utilization of HO-1 enzymatic inhibitors showed a strong reduction of prostate, lung and glioblastoma cells proliferation [27] and in murine and human melanoma cell lines HO-1 overexpression resulted in significantly augmented proliferation [28]. Here, HMOX1 is linked to melanoma.