MAPK3 and glioblastoma: In particular, in U87, LN18, and A172 human glioblastoma cell lines, VEGFR-1 stimulation by both PlGF and VEGF-A resulted in VEGFR-1 phosphorylation at Tyr 1213, followed by downstream phosphorylation of ERK1/2, increased chemotaxis and invasiveness [145].