This is a single arm Phase II study. Patients should begin therapy within 7 working days of study entry. Patients will be treated with omeprazole 80 mg orally twice a day (BID) beginning 4-7 days prior to chemotherapy and continuing until surgery. After the brief period of omeprazole monotherapy, patients will begin standard neoadjuvant chemotherapy with doxorubicin (60 mg/m2) and cyclophosphamide (600 mg/m2) for 4 cycles followed by paclitaxel (80 mg/m2) weekly x 12. Doxorubicin and cyclophosphamide (AC) may be administered on a classical every 3 week or dose dense every 2 week (with growth factor support) schedule at the treating physician's discretion. Routine incorporation of carboplatin is not recommended, however use of carboplatin (AUC 6 on week 1, 4, 7, and 10) with paclitaxel is allowed at the treating investigator's discretion. Chemotherapy will be adjusted based on toxicity according to standard treatment guidelines. Patients with overt disease progression during AC should move immediately to paclitaxel therapy. Patients with disease progression during paclitaxel should proceed immediately to surgery.