RASA1 and non-small cell lung carcinoma: To examine whether RASA1 and FIH-1 play important roles in miR-31-mediated acquired resistance to gefitinib of NSCLC cells, we silenced RASA1 and FIH-1 expression in miR-31-knockdown PC9GR cells and then assessed the sensitivity of PC9GR cells to gefitinib.