(a) Expression of Smad4 as indicated by IRS in lobular and ductal breast carcinoma compared to surrounding normal lobular and ductal breast epithelia of the same specimen (n = 50). Median, 1. and 3. quartile, highest and lowest IRS-value are shown (p < 0.001, sign-test). (b) Correlation according to Spearman between expression of Smad 4 and expression of TβRI (upper panel) and TβRII (lower panel), respectively (n = 197). For each IRS value of Smad4 the median IRS of TβRI and TβRII is denoted by a square. For exploratory reasons a regression line is fitted.