MAPK3 and neuroblastoma: Furthermore, identified downstream targets of ALK detected in this phosphoprofiling, such as mitogen-activated protein kinase (MAPK)1, MAPK3 [extracellular signal-related kinase (ERK)2/1], glycogen synthase kinase-3α, STAT3, FAK, and CRKL (Table S1), showed decreased phosphorylation upon abrogation of ALK activity in several neuroblastoma cell lines (Fig. S1).