Signal transduction
Since G protein–coupled receptors are known to activate Signal transduction in cells, it should not be surprising to find MC1R involved in development. As one example at the cellular level, preventing signalling by MC1R stopped erythropoiesis from proceeding from the polychromatic cell stage (poly-E in the figure) to the orthochromatic cell stage (ortho-E in the diagram). The same report showed that neutralizing antibodies to MC1R prevented phosphorylation of STAT5 by erythropoietin, and that MC2R and MC5R were also involved, as shown in their model.