Activation of TKRs and their downstream pathways in human samples and in TNBC cell lines. A) Human samples of triple negative breast cancer patients were processed for protein extraction. Lysates containing 1 mg/ml protein were analyzed for the level of tyrosine phosphorylation in a panel of 42 receptor tyrosine kinases (RTKs) and citosolic kinases using antibody array kits. The levels of phosphorylated EGFR, HER2, HER3, PDGFRβ, Akt (S473), Akt (T308) and Erk1/2 are shown (indicated by arrows). B) Relationship between pPDGFRβ and pEGFR and AR expression in human samples. Activated PDGFRβ and EGFR obtained from the antibody array kit were measured using a gray level scale in arbitrary units. AR expression measured by western blot was classified in two groups: negative or positive. Statistical difference (p < 0.05) was analyzed using a Mann–Whitney test. C) Eight cell lines Hs578T, MDA-MB231, MDA-MB435, HCC 1187, HBL 100, BT 549, HCC 70 and HCC 3153 were cultured and cell lysates were analyzed by western blot for the levels of different proteins as well as their phosphorylated forms.