Skin (Marvel Comics) had a greyish tone and, because of the extra amount, gave him the appearance of a melted candle. At one point, along with compressing his skin tighter against his body, Skin was learning to manipulate the pigment melanin in his epidermis in order to appear normal. However, performing these two stunts together caused him to have migraines and he soon gave up on the idea of being normal. In the alternate timeline of the Age of Apocalypse, Skin was featured in "Generation Next" as one of the protégés tapped by Colossus and Shadowcat to rescue Illyana Rasputin from enslavement at
Pigment dispersing factor mRNA levels, while PDF knockouts show reduced protein. Similar behavioral and molecular phenotypes are observed in loss of PDF and VIP receptors. Pigment dispersing factor Pigment dispersing factor (pdf) is a gene that encodes the protein PDF, which is part of a large family of neuropeptides. Its hormonal product, pigment dispersing hormone (PDH), was named for the diurnal pigment movement effect it has in crustacean retinal cells upon its initial discovery in the central nervous system of arthropods. The movement and aggregation of pigments in retina cells and extra-retinal cells is hypothesized to be under a split hormonal control mechanism.