(a) COS-7 cells were transfected with Flag-SRC, or not transfected (*), and treated with probe 3 (2 μM, 30 min), followed by washout for the indicated times. After lysis in the presence of sodium borohydride and TAMRA-azide conjugation, samples were analyzed by in-gel fluorescence and western blotting. (b) Normalized fluorescence intensity of ~65 kDa band corresponding to Flag-SRC (mean ± SD, n = 3).