NKX2-1 and lung cancer: Moreover, the mutation rates of AQP4, CLDN18, FOXA2, NKX2-1, PGC, SFTPB, SFTPC, and SFTPD were 3, 5, 2.4, 9, 2.8, 1.8, 5, and 1.1% of the investigated lung cancer samples, respectively (Figure 5(a)).