PTPROt inhibits ERK phosphorylation. Tet-inducible FLAG-tagged WT or mutant (DA and CS) PTPROt clones were cultured with or without Dox, serum starved, and stimulated with goat anti–human IgG (10 μg/mL) for 8 minutes or left untreated. Thereafter, total cell lysates were size fractionated, blotted, and analyzed with anti–phospho-ERK1/2 antibody (top panel). The blot was then stripped and reprobed with anti-ERK1 (middle panel) and anti-FLAG antibodies (bottom panel).