Xie et al. (2018) demonstrated that the BCRC-3 is downregulated in BC, which is capable of acting as a miR-182-5p sponge to influence the expression of p27, thus blocking the growth of BC cells. CircZKSCAN1 and circITCH boost the expression of P21, thus playing a role in BC inhibition by function as sponging for miR-1178-3p and miR-224/miR-17. Simultaneously, circITCH can also enhance PTEN expression, an inhibitor of PI3K/AKT signaling, thus delaying the BC progression (Yang et al., 2018; Bi et al., 2019) (Figure 3). This evidence concerns the gene CDKN1B and breast cancer.