Fig. 2. Inverse bell–shaped dose-response profile of cell death.
(A) Median cell death times (squares) for wild-type HeLa (HeLa wt) and CD95-HeLa cells. Error bars represent SDs from medians in different microscopic fields. (B) Receptor oligomerization model topology, in which receptor (R) trimers bound to ligands (L) represent active receptors Ractive. (C) Mechanism of inverse bell–shaped behavior. At high ligand concentrations, most bound ligands are connected to receptors in a 1:1 stoichiometry, resulting in a low number of oligomerized receptors capable of caspase-8 activation. (D) Simulations for active receptor fractions for CD95-HeLa and HeLa wt cells calculated with kinetic parameters from model fitting. Ract, Ractive.