circRNA DONSON, overexpressed in gastric cancer (GC), modulates the levels of the PRC1 component BMI1 via miR-802 sponging (Y. Liu et al., 2020b) and promotes CG proliferation and invasion by regulating SOX4 expression through directly recruiting the ATP-dependent nucleosome remodeling factor (NURF), a chromatin remodeling complex (Ding et al., 2019) (Figure 3C). Here, BMI1 is linked to gastric cancer.