To understand better the changes that occur just within DCIS as they progress closer to the transcriptomic patterns of IDC, we compared DCIS samples from the early part of the PCP (Fig. 3b, E1-E2) with DCIS samples from the later part of the PCP (Fig. 3b, L1–L2) we found that a number of smooth muscle related genes were down regulated in the later stages with TAGLN, CALD1, MYL9 and ACTA2 being most significant (Fig. 3c and Supplementary Data 2). This evidence concerns the gene MYL9 and ductal breast carcinoma in situ.