We confirmed that PPP2R2B-associated PP2A targets p70S6K and 4EBP1 for dephosphorylation, and thus reduced expression of PPP2R2B in breast cancer cells is associated with diminished p70S6K and 4EBP1 dephosphorylation by anti-HER2 treatment. Here, RPS6KB1 is linked to breast carcinoma.