Thus, the PR-PPD present in the BR2-2xPPD, once internalized, can directly compete with the PPD in SOS to bind to the Grb2-SH3 domains, leading to a suppression of Grb2-SOS signal transduction, a significant reduction in Erk1/2 activation and a decrease in NSCLC cell proliferation. The gene discussed is GRB2; the disease is non-small cell lung carcinoma.