Fbw7 isoforms interact in cells (1). A: Homo- and heterodimerization of Fbw7. Differentially tagged Fbw7 isoforms were transfected as indicated and lysates subjected to immunoprecipitations with Flag antibody. B: Fbw7α and Fbw7γ heterodimerize. Identical assay as in A, except 5-fold lower amounts of each isoform were expressed. C: Heterodimerization of Fbw7α and Fbw7γ occurs in cells. U2OS cells grown on cover slips were co-transfected with Flag-Fbw7γ and Myc-tagged versions of either Fbw7α, the Fbw7α dimerization mutant, or Fbw7β. Cover slips were fixed and co-stained with Flag and Myc antibodies.