Correlations between MBP-1, HDAC1 and ErbB2 protein expression in primary breast tumors. Correlation plot for MBP-1 versus HDAC1 (A), MBP-1 versus ErbB2 (B) and HDAC1 versus ErbB2 (C) protein levels. Black squares and coloured triangles represent expression values determined by immunohistochemical staining of 45 breast IDCs, as described in Materials and Methods. Blue lines represent the linear regression, dotted lines the 95% CI. The coefficient of correlation (r) was determined and its statistical significance was tested using the nonparametric Spearman rank correlation test.