Fig. 4.

Effect of γ-radiation on phospho-BTK (-Tyr550) and phospho-Gab2 (Tyr643) levels in normal human fibroblast cells. MRC-5 and NHDF cells were exposed to γ-radiation at the indicated doses and then incubated for 0.5 h. (A) Phospho-BTK (Tyr550), BTK, phospho-Gab2 (Tyr643) and Gab2 protein expression levels in MRC-5 cells were determined by western blotting (top). The protein levels were calculated by densitometry and normalized with respect to unphosphorylated proteins. (B) Protein levels in NHDF cells were detected with the corresponding antibodies using MRC-5 cells (top). The consensus protein levels were analyzed by densitometry. γ-H2AX was used as a biochemical marker for DNA damage. β-actin was used as a loading control.