We next observed that, in TCGA Pan Cancer Atlas as well as in breast, lung, brain, prostate and skin cancer patients (see Materials and Methods) in addition to high-grade gene amplification, also low-grade variations (i.e. low-copy gain and shallow deletions) in CBX3 gene strongly co-occur with low-grade variations of either EGFR or RAC1 genes (Fig. 6A–F; Supplementary Fig. 9A–F). Here, RAC1 is linked to skin cancer.