Unsupervised hierarchical clustering of in situ and invasive samples. (a) Dendrogram of all in situ (n = 40) and all invasive (n = 40) samples. (b) Scaled-down representation of the entire cluster shown in (a) (1,706 genes). (c) Dendogram of poorly differentiated ductal carcinoma in situ (n = 14) and grade 3 invasive (n = 24) samples. (d) Entire cluster of (c) (1,119 genes). Yellow indicates in situ samples, and blue indicates invasive samples. i, intermediately differentiated; IHC, immunohistochemistry; i/p, intermediately/poorly differentiated; LCIS, lobular carcinoma in situ; p, poorly differentiated; w, well differentiated; w/i, well/intermediately differentiated.