P4HA1 and glioma: We selected P4HA1 for further investigation because (i) P4HA1 showed the highest expression level among these 6 proteins in CRC tissues, (ii) P4HA1 overexpression has shown positive correlation with tumor progression in breast cancer, prostate cancer, and high-grade glioma [15–17], and (iii) prognostic relevance of P4HA1 in CRC has not been studied.