MAPK3 and neoplasm: We have recently described a cell surface receptor for thyroid hormone on integrin αvβ3 [11] that is linked to activation of ERK1/ERK2 (extracellular signal regulated kinase 1/2 [ERK1/2]) and, downstream of ERK1/ERK2, to complex transcriptional events, such as tumor cell proliferation [8] and angiogenesis [10].