circCDYL2 inhibits the binding of Pin1 with the GRB7 by interacting with GRB7, which leads to a decrease in the ubiquitination level of GRB7 and thereby stabilizes the expression of GRB7, resulting in the up-regulation of the GRB7 protein expression in HER2-positive breast cancer cells. Here, GRB7 is linked to breast carcinoma.