Supplementary Figures from Extracellular Matrix/Integrin Signaling Promotes Resistance to Combined Inhibition of HER2 and PI3K in HER2<sup>+</sup> Breast Cancer

Supplementary Figure 1. HER2+/PIK3CAH1047R mammary tumors acquire resistance to trastuzumab + pertuzumab + BKM120 in vivo. Supplementary Figure 2. Primary tumor cells (PTCs) derived from TPB-resistant tumors are sensitive to TPB in vitro. Supplementary Figure 3. Collagen reduces sensitivity to TPB in human breast cancer cells. Supplementary Figure 4. TbRI inhibition does not affect Collagen-induced TPB resistance. Supplementary Figure 5. Collagen deposition is enhanced in residual drug-resistant tumors following neoadjuvant anti-HER2 therapy.