PTPROt inhibits SYK tyrosyl phosphorylation. Tet-inducible FLAG-tagged WT or mutant (DA and CS) PTPROt clones were cultured with or without Dox, serum starved, and stimulated thereafter with goat anti–human IgG (10 μg/mL) for 8 minutes or left untreated. Cells were lysed and immunoprecipitations were performed with anti-SYK antibody. The phosphorylation of SYK was detected by Western blot with the antiphosphotyrosine antibody 4G10 (top panel). The blot was then stripped and reprobed with anti-SYK (bottom panel).