ERBB2 and breast carcinoma: We considered phosphorylated ERK (pERK), Akt (pAkt), and c-Fos (pc-Fos) to be key determinants of this network and measured time course patterns of these proteins in four breast cancer cell lines, MCF-7, BT-474, SK-BR-3, and MDA-MB-231, which represent different breast cancer subtypes, Luminal A, Luminal B, HER2-positive and Triple-negative, respectively [34].