In our study, overexpression of FOXP1 in TICs resulted in decreased proliferation and sphere-forming capacity of TICs in vitro, and a decrease in stem cells markers (CD44, CD133, and ALDH1A3) and H3K9Me2 compared to control cells, which is consistent with its tumor suppressor function in NSCLC in tumor initiation and progression. The gene discussed is FOXP1; the disease is neoplasm.