Table 3:

Parameter values for ligand dynamics and receptor activation

symb.	parameter	value	reference
${\mu }_1$	assoc. rate EP2 - PGE2	0.2417(sμM)−1	[15] (calculated from $K_d$, mouse)
${\mu }_2$	assoc. rate EP4 - PGE2	1.385(sμM)−1	[36] (human embryo. kidney cells)
${\delta }_1$	dissoc. rate EP2 - PGE2	0.0029 s−1	[20] (CD95L, DcR3 decoy receptor)
${\delta }_2$	dissoc. rate EP4 - PGE2	0.03325 s−1	[36] (human embryo. kidney cells)
${\rho }_1$	internalization rate EP2	0	assumed
${\rho }_2$	internalization rate EP4	0.00538 s−1	[23] (estimat., human 293-EBNA)
$n_1/n_2$	Hill coefficient EP2 /EP4	3/1	assumed
$r_1^{tot}$	total EP2 concentration	2–5nM (4nM)	[37, 4] (human T-cells)
$r_2^{tot}$	total EP4 concentration	8nM	assumed
$\sigma$	binding ratio for crosstalk	0.5	assumed