PPM1F and hepatocellular carcinoma: We examined the expression levels of PPM1F in multiple gastrointestinal tumors using the TCGA database and found that PPM1F had the most obvious upregulation in paired (n = 50, P < 0.0001; Fig. 1a1) and unpaired HCC tissues (n = 372, P < 0.0001; Fig. 1a2) as compared with the other tumor tissues.