Fig. 7: MMP13 expression is associated with invasion in a mouse model of DCIS and in human samples.

a Representative Mmp13 RNAscope images of non-invasive and invasive fronts from MCF7-MIND mice at 12 weeks post intraductal injection. Mmp13 expression is indicated by presence of red dots. Graph shows number of Mmp13⁺ cells per 250 µm field of view. n = 3 mice. Scale bar = 50 µm. b Summary graph showing percentage of MMP13 positive patients across normal (n = 10), DCIS (n = 10) and IDC (n = 10) cases. c Representative images of β6 IHC (brown) staining and MMP13 RNAscope (red) detection in normal and DCIS patients. Scale bar = 100 µm. d Graph showing percentage of MMP13 and β6 positive cells/per duct across DCIS patients. Data are presented as individual points where each dot represents one duct, with different patients represented by different colours (12 DCIS ducts quantified per patient) (Simple linear regression). e Schematic showing proposed mechanism where myoepithelial β6 expression drives TGFβ-dependent activation of EP300 to regulate MMP13 expression.