FOLR1 and cancer: In conclusion, this study provides important basic data on the changes in pemetrexed-related transporters and receptors after long-term fractionated irradiation and suggests that the pemetrexed-decitabine combination is a promising treatment option that sensitizes radioresistant LUAD cells to pemetrexed by increasing the FRα-mediated accumulation of pemetrexed in cancer cells.