Using the potent GR agonist, dexamethasone (DEX), we discovered GR agonists cause G1/S cell-cycle arrest via up-regulation of CDKN1C in responder NSCLC lines and that growth inhibition occurred in lung adenocarcinoma and squamous tumor lines with and without other oncogenic mutations such as KRAS. The gene discussed is KRAS; the disease is lung adenocarcinoma.