Among all HER2-IHC 3+ breast tumors (Tumor 0119, 0301, 0903, 0909), we found a 5-fold difference in p185HER2 expression (AVGHER2, t0909 = 6.3 ± 4.1 × 106 (s.d.), n = 90 HER2-positive cells; AVGHER2, t0119 = 1.2 ± 0.54 × 106 (s.d.), n = 36 HER2-positive cells). The gene discussed is ERBB2; the disease is breast neoplasm.