\frac{dx_{1}}{dt} = \left(1 \cdot k_{12} \cdot k_{2} / \left(1 + k_{6} \cdot \left(1 + x_{3} / k_{7}^{k_{9}}\right)^{k_{8}}\right) + -1 \cdot k_{12} \cdot k_{3} \cdot x_{1}\right) / k_{12}\\
\frac{dx_{2}}{dt} = \left(1 \cdot k_{12} \cdot x_{1} + -1 \cdot k_{12} \cdot k_{4} \cdot x_{2}\right) / k_{12}\\
\frac{dx_{3}}{dt} = \left(1 \cdot k_{12} \cdot k_{1} \cdot x_{2} + -1 \cdot k_{12} \cdot k_{5} \cdot x_{3}\right) / k_{12}