Fig 1: Association of Stx4 1 to 15 with Munc18c inhibits Stx4–SNAP23 interaction. A, Parental MDA-MB-231 cells, and cell lines stably expressing GFP, GFP-Stx4-1-15, or GFP-Stx4-15-29 were lysed, and GFP was immunoprecipitated. Immunoprecipitates (IP) were probed for Munc18c. B, Parental MDA-MB-231 cells, and cells stably expressing Stx4-FL. Stx4–N-term, Stx4-1-15, or Stx4-15-29 were lysed, and SNAP23 was immunoprecipitated. IPs were probed for Stx4 and SNAP23. C, Densitometry of the amount of Stx4 coimmunoprecipitated relative to SNAP23 as shown in B (*, P < 0.05). Data represent three or more biological replicates with at least three technical replicates. B+a, beads plus antibody; B+L, beads plus GFP lysate. IB, immunoblot.