DKK1 and melanoma: However, it was recently reported that the signaling molecules Dickkopf-1 (DKK1) stimulated from a melanoma cell line treated by neural stem cells-conditioned medium (NSC-CM) indirectly inhibited pigment formation by decreasing the intracellular expression levels of TYR and other melanogenic enzymes as well as MITF [44] (Table 1).