To explore the expression of the calp/cast system components in human GBM, we analyzed by GEPIA (http://gepia.cancer-pku.cn/) (Tang Z. et al., 2019) the mRNA expression level of the calp/cast axis in normal brain (207 samples), low-grade glioma (LGG, 518 cases) and high-grade glioma (GBM 163 cases) based on the Cancer Genome Atlas (TGCA) and Genotype-Tissue Expression (GTEx) database (Figure 2A). The gene discussed is KCNIP4; the disease is cancer.