Analysis of HER family members and associated signaling pathways in representative vehicle- and Pan-HER-treated TNBC PDXs. a Representative PDX tumor models BCM-2665, BCM-3107 (subgroup 2), BCM-4913, and BMC-3555 (subgroup 1) treated with either vehicle control or Pan-HER for 3 cycles were collected at the end of the experiment (day 21 following the initial injection) and analyzed by Western blot (a) or immunohistochemistry (b). Western blot analysis of tumor lysates was used to determine HER family members EGFR and HER3, as well as associated signaling pathways including pEGFR, pHER3, FAK, AKT, and ERK pathways. A representative image is shown. β-actin levels were used as loading controls. Each Western blot lane corresponds to an individual PDX/mouse of the designated group. b Representative immunohistochemistry analysis of human EGFR and HER3 protein expression was performed in preparations of TNBC tumor samples as described in “Methods”; samples were collected as described above. Counterstain: hematoxylin; here where it says "magnification x 4", it should say "magnification x 20".