Regression analysis of apoptosis under various conditions. Activation time regression coefficients for sample model cases. The activation time is defined as the time at which the peak caspase-3 concentration over the time course occurs. The regression coefficients are ordered by their parameter indices as shown in Table 5. Induction by FasL ([FasL]0 = 2 nM unless noted) corresponds to receptor-mediated apoptosis, while induction by tBid corresponds to mitochondrial apoptosis ([tBid]0 = 25 nM and [FasL]0 = 0 unless otherwise noted). (a) HeLa cell induced by FasL (r2 = 0.9958). (b) Jurkat T cell induced by FasL (r2 = 0.9903). (c) Jurkat T* cell induced by FasL (r2 = 0.9846). (d) Jurkat T* cell induced by low FasL ([FasL]0 = 0.01 nM; r2 = 0.9569). (e) HeLa cell induced by tBid (r2 = 0.9705). (f) Jurkat T cell induced by tBid (r2 = 0.9879). (g) Jurkat T* cell induced by tBid (r2 = 0.8873). (h) Predicted type II apoptosis cell parameters (k-4 = k-6 = 10-3 s-1, [XIAP]0 = 200 nM, [FasR]0 = 1 nM) induced by FasL (r2 = 0.9264).