\frac{dx_{1}}{dt} = 1 \cdot k_{17} \cdot \left(k_{6} \cdot x_{4} - \left(k_{7} \cdot x_{2} + k_{8} \cdot \left(1 - x_{3} / k_{5}\right)\right) \cdot x_{1}\right) / k_{17}\\
\frac{dx_{2}}{dt} = 1 \cdot k_{17} \cdot \left(k_{9} \cdot x_{4} + k_{11} \cdot x_{3} - \left(k_{10} \cdot x_{1} + k_{12}\right) \cdot x_{2}\right) / k_{17}\\
\frac{dx_{3}}{dt} = 1 \cdot k_{17} \cdot \left(\left(k_{13} \cdot \left(1 - x_{3} / k_{5}\right) + k_{14} \cdot x_{2} - k_{15} \cdot x_{4}\right) \cdot x_{3} + \exp\left(\left(-1\right) \cdot k_{16} \cdot t\right)\right) / k_{17}\\
\frac{dx_{4}}{dt} = 1 \cdot k_{17} \cdot \left(\left(k_{1} \cdot x_{2} + k_{2} \cdot x_{3}\right) \cdot \left(1 - x_{4}\right) - \left(k_{3} \cdot x_{1} + k_{4} \cdot \left(1 - x_{3} / k_{5}\right)\right) \cdot x_{4}\right) / k_{17}