ERBB2 and neoplasm: Interestingly, Ptp1b−/−; MMTV-neu exhibited a greatly reduced tumorigenesis of neu tumor (27% mice formed tumors at 69 weeks) as comparing with Ptp1b+/−; MMTV-neu and Ptp1b+/+; MMTV-neu (T50 = 61 weeks and 57 weeks respectively).