MAPK3 and cancer: On the other hand, the extracellular T4 or to a less extend T3 can, via a specific receptor on a plasma membrane integrin αvβ3, activate extracellular signal-regulated kinses (ERK1/2) and downstream signal transduction pathways to promote cell proliferation in variety types of cancer cells [6, 13, 33, 58, 71, 84].