DCIS cells adjacent to invasive disease show significantly higher expression of ECM remodeling proteases cathepsin V and cathepsin A, prolyl 4-hydroxylase A2 (involved in collagen synthesis) and fibrillar collagen component COL11A1, compared to DCIS cells from pure lesions (Table 5), suggesting the expression of these proteins aids in the DCIS-IDC transition. This evidence concerns the gene COL11A1 and ductal breast carcinoma in situ.