MEK-1 activates C-Raf through a Ras-independent mechanism

► MEK overexpression induces C-Raf hyper-phosphorylation and activation. ► Co-expression of wildtype C-Raf and MEK constitutively activates ERK MAPK. ► MEK-induced C-Raf activation is Ras independent. ► MEK-induced C-Raf activation requires C-Raf-MEK interaction. ► MEK is a novel, Ras-independent C-Raf activator.