ERBB2 and breast cancer: To test the hypothesis that chronic dietary PR was more effective than intermittent fasting (IF) in inhibiting tumor growth in an animal model of human breast cancer, we acclimatized 4–6 week old female NOD-SCID mice to either a 21% or 7% (PR) protein diet, fed ad libitum or intermittently (IF) for 4 weeks, prior to subcutaneous implantation of WHIM16 ER+/PR-/HER2- tumor cells.