PENK and hepatocellular carcinoma: The top 15 hub genes were as follows: LPAR3, CXCL9, CXCL10, CXCL11, PF4, PPBP, CCL19, SST, GAL, NPY1R, CCL25, CCR10, PENK, OPRK1 and CNR1. Additionally, we determined the expression levels of the top 15 hub genes between HCC tissues (non-cirrhotic HCC tissues or cirrhotic HCC tissues) and HCC normal tissues in TCGA.