Visualization of RAS/MAPK Signaling In Situ by the Proximity Ligation Assay (PLA).

RAS/MAPK signaling responds to diverse extracellular cues and regulates a wide array of cellular processes. Given its biological importance, abnormalities in RAS/MAPK signaling cascade have been intimately implicated in numerous human diseases, including cancer. Herein, we describe a novel methodology to study activation of this pivotal signaling pathway. The Proximity Ligation Assay (PLA) is employed to monitor kinase-substrate interactions between MEK1 and HSF1, or MEK1 and ERK1 in situ.