NADK2 and cancer: Figure 6A demonstrates the interaction network of these proteins. The GEPIA2 tool was used to combine all brain cancer tumor expression data in the TCGA databased and determined the top 100 genes that correlated with AQP4 expression. As shown in Figure 6B, the AQP4 expression level correlated positively to that of MLC1 (R = 0.83), NADK2 (R = 0.38), SLC7A11 (R = 0.26), RFX4 (R = 0.81), and CERS1 (R = 0.82) genes (all p < 0.001). There was also a positive association between AQP4 and the above five genes across various different cancers (Figure 6C).