Table 4. Variables Minimal Model of WNT signaling.

Model name	Variable	Compound	Values obtained from	WNT OFF (nM)	WNT ON (nM)
CB	$x_1$	Free cytoplasmic CTNNB1	FCS data this report	91	145
DC	$x_2$	Free destruction complex	Model equations	82.4	52
CB*-DC	$x_3$	DC-bound phosphorylated CTNNB1	FCS data this report*	62.5*	62.5*
DC*	$x_4$	Inactivated destruction complex	Model equations	0**	30.5**
NB	$x_5$	Free nuclear CTNNB1	FCS data this report	87	170
TCF	$x_6$	Free TCF	Model equations	81	17
NB-TCF	$x_7$	TCF-bound nuclear CTNNB1	FCS data this report	22.2	86
TCF0	${\mathrm{T}\mathrm{C}\mathrm{F}}^0$	Total TCF	$x_7$ and Tan et al., 2012 - Figure 11	103	103

^*Under the assumption that k3 does not change, the levels of CB*-DC remain equal. Since there was no significant difference between the concentration of slow SGFP2-CTNNB1 in the absence or presence of WNT3A (57 nM versus 68 nM, not significant, Table 2) the average of both medians (62.5 nM) was used. ** In WNT OFF, w=0, and no inactivated destruction complex is formed. In WNT ON, w=1, which induces the formation of inactivated destruction complex at the expense of free destruction complex (see Equations 7a and 9 in the model description in Materials and methods).