MAPK3 and neoplasm: In view of the tumor‐promoting capacity of prolonged stress, here we investigated (a) the effect of urocortin on cell proliferative signaling via extracellular signal‐regulated kinase 1/2, (b) the expression and cellular distribution of the specific CRF receptor isoforms, and (c) the intracellular localization of phosphorylated ERK1/2 in HeLa cells.