PLA using Duolink® PLA kit was performed on DCIS.COM cells using anti-β-catenin and anti-BCL9 antibodies (Supplementary Fig. 4b: top), or anti-PS-727-STAT3 and anti-BCL9 antibodies (Supplementary Fig. 4b: bottom). Here, BCL9 is linked to ductal breast carcinoma in situ.