HDAC1 and breast neoplasm: We also report a significant inverse correlation between ERBB2 expression and both MBP-1 (r= −0.278, p= 0.031) and HDAC1 (r= −0.267, p= 0.037) protein levels in primary breast tumors, and, accordingly, we propose MBP-1/HDAC1/ERBB2 relative expression as a diagnostic marker in breast IDC.