PIK3CD and breast cancer: Then, IHC and Western blotting were used to detect the levels of WWP1 and pS473-AKT in tumor tissues, and it was found that WWP1 and pS473-AKT were expressed at low levels in the sh-circWAC and sh-circWAC +PTX groups (Fig. 9d, e), proving that decreased expression of WWP1 causes inactivation of the PI3K/AKT signaling pathway and leads to an increase in the sensitivity of breast cancer cells to chemotherapy.