Figure 1 Troponin C1, slow skeletal and cardiac type (TNNC1) was significantly upregulated in gemcitabine (GEM)-resistant nonsmall-cell lung cancer cells and serum of the patient. (A1, A2) TNNC1 was significantly upregulated in GEM-resistant Calu3 cells (Calu3-GemR) compared with the parental Calu3 cells (Calu3-parental) by analyzing the Gene Expression Omnibus Data Set log fold change >1.0 or <−1.0, P<0.05). (B) TNNC1 was significantly increased in lung adenocarcinoma cancer tissues (Tumor) compared with adjacent tissues (Normal) (data sources Gene Expression Profiling Interactive Analysis database). (C) Expression of TNNC1 in clinical serum samples using reverse tracscription-quantitative polymerase chain reaction (RT-qPCR). Resistance group vs. sensitive group; data presented as mean±SD, * P<0.05 (D, E). Relative expression of TNNC1 and forkhead box 03 (FOXO3) in A549/GemR cells and A549 parental cells detected by RT-qPCR (D) and western blot (E) respectively (*** P<0.001).