PPIA and squamous cell lung carcinoma: The expression levels of PPIA increased with increasing cancer stage in bladder carcinoma, breast invasive carcinoma, esophageal carcinoma, kidney chromophobe, kidney renal clear-cell carcinoma, kidney renal papillary cell carcinoma, liver hepatocellular carcinoma, lung adenocarcinoma, and lung squamous cell carcinoma (Figure 6A).