In addition, expression of four genes (IGSF9, AGRN, STAP2 and PKP4) was significantly up-regulated in advanced NPC patients of the data set GSE102349 (Additional file 1: Fig. S3b), but expression of other three genes (TRIP6, EPCAM and IRF6) was not. Here, EPCAM is linked to nasopharyngeal carcinoma.