NAP1L4 and hepatocellular carcinoma: In discovery stage (I), based on a series of criteria (P < 0.05, fold change ≥ 2, the sensitivity ≥ 60%, the specificity ≥ 90%, the Youden index ≥ 50%, and the significant elevation of the value of SNR in HCC group compared to that in NC group) by the intersection of the calculation methods (Z‐score and median normalization), 15 candidate TAAs (RUNX1T1, RAD23A, CAST, PRKCZ, SF3B3, SARS, DUSP6, PAIP1, SH2B1, NAP1L4, CRLF3, LARP6, NOL7, MAGEA12, and CCDC6) were screened out from Human Proteome Microarray.