SPP1 and nasopharyngeal carcinoma: To validate the expression of 25 core genes in NPC tissues, we uploaded the 25 core genes to GEPIA database and there were 10 core genes were revealed to be significantly over-expressed in NPC tissues contrasted to normal nasopharyngeal tissues, including FN1, MMP1, MMP3, PLAU, PLAUR, SERPINE1, SPP1, COL8A1, COL10A1 and COL17A1, which were consistent with GSE40290 and GSE53819 (P < 0.05, Fig. 5).