Fig. 1

Inhibition of EGFR and HER2 tyrosine kinases suppresses radiation-activated MMP-9 expression. a LLC cells exposed or unexposed to radiation (RT) (7.5Gy) were treated with afatinib (100 nM), erlotinib (1 μM), or control. After 2 h, pEGFR and pHER2 in total cell lysates was detected by Western blotting, with β-actin as a loading control. RT increased both pEGFR and pHER2, which were inhibited by afatinib. But erlotinib only inhibited pEGFR. b RT-PCR assay showed that RT increased MMP-9 expression, which was significantly reduced by afatinib and erlotinib. Gene expression was measured relative to the sham control. * indicating p < 0.05. c After 12 h post-RT, MMP-9 in the total cellular lysate was detected by Western blotting; d The total MMP-9 concentrations in the culture supernatant were detected. * indicating p < 0.05; e MMP-9 activities were determined using gelatin zymography