Figure 2.

A schematic representation of the Raf–MEK–ERK signaling cascade, including the KSR scaffold protein in cells. In quiescent cells, the KSR scaffold protein is typically cytoplasmic and constitutively bound to MEK and 14–3-3. Upon receptor tyrosine kinase (RTK) stimulation, signaling cells initially utilize KSR to enhance signal transmission from Raf to MEK by facilitating Raf/MEK interaction. Subsequently, KSR attenuates signaling by docking activated ERK. Overall, KSR regulates the intensity and duration of Raf–MEK–ERK signaling cascade activation.