1. PTB-independent ShcA pools require a functional SH2 domain, but not the tyrosine phosphorylation sites to promote mammary tumorigenesis.
PTB-independent ShcA pools require a functional SH2 domain, but not the tyrosine phosphorylation sites to promote mammary tumorigenesis. A, Schematic diagram illustrating how the ShcA PTB domain coordinates distinct intracellular signaling complexes that initiate and amplify mammary tumorigenesis in ErbB2-driven breast cancers. Schematic representation of ShcA alleles employed in this study is also shown. B, Immunoblot analysis characterizing the expression of FLAG-tagged PTB domain mutant ShcA alleles in ErbB2-driven mammary epithelial cell lines (NMuMG-NeuNT). C, MMTV Middle T antigen mammary epithelial cells expressing indicated Myc-BirA fusion proteins were subjected to BioID analysis. Biotinylated proteins were probed using the indicated antibodies by immunoblot analysis. D, Grb2 interactions assessed by the immunoprecipitation of FLAG-tagged PTB domain mutant ShcA alleles expressed in NMuMG-NeuNT cells. Number (E) and average area (F) of foci formed in a soft agar assay from the indicated cell lines. The data is representative of three independent experiments (means ± SEM). ShcAWT vs. PTBMUT: **, P < 0.01; ****, P < ; PTBMUT versus PTBMUT/3F or PTB/SH2MUT: δ, P < 0.05; δδ, P < 0.01; δδδ, P < G, Mammary fat pad injection of the indicated cell lines into immunodeficient mice. The data are shown as average tumor volume (mm3) ± SEM and is representative of 14 tumors per group. ShcAWT versus PTBMUT: ***, P < 0.001; PTBMUT versus PTBMUT/3F or PTB/SH2MUT: δδ, P < 0.01; δδδ, P < IHC staining of mammary tumors using Ki67 (H) and cleaved Casp3 (I). The data depicts the average positively stained cells or pixels ± SEM and is representative of 6–8 tumors per group. **, P < 0.01.
Jacqueline R. Ha et al. Mol Cancer Res 2018;16:
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