PIK3CA and breast cancer: For pathways, the two subtypes differ in mutations and copy number alterations of genes in PI3K signaling (\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$p=0.0039$$\end{document}p=0.0039) (Fig. 1; Additional file 2: Table S1), the most altered pathway in canine mammary tumors [33].