NTRK1 and breast cancer: The Src homology phosphotyrosyl phosphatase2 (SHP2) is a positiveregulator of receptor tyrosine kinase (RTK) signaling,1−6 and by doing so it promotes the cancerous phenotype of tumor cells,including breast cancer.7,8 For instance, SHP2 promotesthe transformation phenotypes of the HER2-positive (HER2+) and thetriple-negative breast cancer (TNBC) cells, including epithelial tomesenchymal transition in 2D culture, colony formation in soft agar,mammosphere formation in suspension cultures, extracellular matrixdegradation and invasion in 3D matrigel, and tumorigenesis in vivo.