(A) List of the top candidate MAGI3-interacting proteins in MCF10A cells as identified by AP-MS. (B) Endogenous MAGI3/YAP interaction in MCF10A cells by co-IP. Immunoblots of MAGI3 and YAP from input and indicated IP lysates are shown. (C) Immunoblots of full-length MAGI3-V5 and either full-length Flag-YAP (left) or mutant Flag-YAPΔC (right), in which the C-terminal YAP PDZ-binding motif (FLTWL) is deleted, from the indicated input and IP lysates (HEK293T cells). (D) Immunoblots of full-length YAP and either full-length MAGI3-V5 or PDZ6-deleted MAGI3-V5 from the indicated input and IP lysates (HEK293T cells). (E) The relative expression of YAP target genes ANKRD1 and CYR61 in MCF10A cells, as determined by qPCR, in cells expressing shMAGI3 or non-silencing Scr control, with or without MAGI3 cDNA or non-rescuing GFP control (n = 3 technical replicates per cell line). Data are presented as mean ± SEM. *p<0.05, **p<0.01, ***p<0.001 (two-tailed Student’s t-tests). (F) Anchorage-independent growth assays for MCF10A-SV40 cells expressing the indicated shRNA and/or cDNA constructs. Images show representative soft agar fields and insets show commonly observed colony sizes for the indicated cell lines after three weeks. Scale bar represents 100 µm. (G) Quantification of transformed colonies in the indicated cell lines (n = 3 biological replicates per cell line) after three weeks (upper panel). Immunoblots of full-length MAGI3 isoforms, YAP and β-actin levels in the cell lines (lower panels). Data are presented as mean ± SEM. **p<0.01, ***p<0.001 (two-tailed Student’s t-tests).