Fig. 6. PRL-induced mammary cancers exhibit an upregulation of ErbB receptor tyrosine kinases.

(a) Western blot analysis to determine the expression of all four ErbB family members in NRL-PRL-induced mammary cancers as well as normal mammary glands (MG) from lactating NRL-PRL females. (b) Immunoprecipitation (IP) and western blot (WB) analysis to assess the tyrosine phosphorylation and heterodimer formation of ErbB2 and ErbB3. (c) Western blot analysis to assess the expression of ErbB receptors in untransformed and neoplastic mammary epithelial cells that lack Jak2 and their isogenic controls expressing Jak2. Beta-Actin (ActB) served as a loading control in both panels.