Model is underconstrained.
The following variables couldn't be defined:
 * Ca_i in component Ca_i
 * J1 in component Ca_i
 * J2 in component Ca_i
 * Ca_ER in component Ca_ER
 * P_open in component probability_of_an_open_IP3_receptor_channel
 * V1 in component fluxes
 * V3 in component fluxes
 * V4 in component fluxes
 * V2 in component fluxes
 * x_011 in component x_011
 * d/dt Ca_i in component Ca_i
 * d/dt IP3 in component IP3
 * d/dt x_000 in component x_000
 * d/dt x_001 in component x_001
 * d/dt x_010 in component x_010