Expression of nonsynonymous sequence variants does not alter cellular phosphotyrosine content. Evaluation of phosphotyrosine levels after expression of mutant DDR1, TEK, and FES. Ba/F3 cells were stably transfected. Cells were serum starved overnight and subjected to immunoblot analysis for phosphotyrosine (4G10) as well as total (A) DDR1, (B) TEK, or (C) FES.