Interaction of 14-3-3 proteins with ETV1. (A) 14-3-3τ, ζ and ε, but not σ, coimmunoprecipitate with ETV1. 6Myc-tagged ETV1 was coexpressed with indicated 14-3-3 proteins in 293T cells. After anti-Myc immunoprecipitation (IP), interacting 14-3-3 proteins were revealed by Western blotting (top). Middle and bottom panels show the presence of 14-3-3 proteins and ETV1, respectively, in the cell extracts. (B) Endogenous coimmunoprecipitation in LNCaP and PC3 prostate cancer cells. After precipitation with ETV1 or control IgG antibodies, coprecipitated 14-3-3ε was detected by Western blotting. (C) Activation of an MMP-1 luciferase reporter construct in 293T cells transfected with ETV1 and/or 14-3-3τ expression plasmids. (D) MMP-1 and GAPDH mRNA levels were determined by RT-PCR analysis of 293T cells transfected with ETV1, HER2/Neu and/or 14-3-3τ. (E) Coimmunoprecipitation of 14-3-3τ with 6Myc-ΔETV1 in 293T cells. (F) Synergy between ΔETV1 and 14-3-3τ/14-3-3ε in inducing MMP-1 transcription in 293T cells.