PIK3CA and breast carcinoma: Synergistic effects of combined Usp7 knockdown and PI3K inhibition were analyzed in murine PyB6-TA as well as human MCF7-TA and MDAMB-TA breast cancer cells, using the miR-E-transduced cell lines that generated the most potent protein reduction after 4 and 8 days of Dox treatment (Figures 6A-D).