LGR5 and colorectal cancer: In order to further target the radiation-resistance genes closely related to tumor repopulation after radiotherapy, we used multivariate regression analysis to condense 252 co-upregulated genes and established a prognostic prediction system, which consisted of four key genes (LGR5, KCNN4, TNS4, CENPH), based on the TCGA colorectal cancer patients (Figs. 2 and 3).