Model for signaling by constitutively active hβc mutants.

Schematic diagram showing the proposed stoichiometry of constitutively active hβc mutant receptor complexes. The cell membrane is represented by a solid bar, with extracellular regions at the top. Stars indicate the positions of activating mutations in hβc. Note that the wild-type mGM-CSFR and mIL-3R may in fact be tetrameric,25 but for simplicity only heterodimers are shown.