ERBB2 and breast cancer: In agreement with the possibility that PEAK1 plays a role in EMT and metastasis downstream of TGFβ, we discovered that breast cancer samples from patients with recurrent metastatic disease or poor prognostic biomarker status (i.e., HER2-positive or TNBC) displayed significantly elevated levels of PEAK1 and TGFβ response genes [31,32,33,34] (S4 Fig).