PIK3CA and breast cancer: Synergistic effects on breast cancer cell growth were observed upon combined Usp7 knockdown and BKM EC10 and EC20 treatment in all three cell lines, indicated by a significantly stronger growth reduction in PI3K-inhibitor-Dox treated cells compared to PI3K-inhibitor-only treated cells (green circles) and DMSO-Dox treated cells (circle radius p ≤ 0.05; Figure 6G).