\frac{dx_{1}}{dt} = \left(1 \cdot k_{17} \cdot k_{16} + -1 \cdot k_{17} \cdot k_{15} \cdot x_{1} + -1 \cdot k_{17} \cdot x_{1} \cdot k_{7} \cdot k_{20} \cdot k_{21} / \left(1 + k_{21}\right) / \left(k_{4} + k_{20} + x_{10}\right)\right) / k_{17}\\
\frac{dx_{2}}{dt} = \left(1 \cdot k_{17} \cdot k_{16} + -1 \cdot k_{17} \cdot k_{15} \cdot x_{2} + -1 \cdot k_{17} \cdot x_{2} \cdot k_{7} \cdot k_{20} \cdot k_{21} / \left(1 + k_{21}\right) / \left(k_{4} + k_{20} + x_{10}\right) + -1 \cdot k_{17} \cdot x_{2} \cdot k_{7} \cdot k_{8} \cdot k_{19} \cdot k_{21} / \left(k_{1} + k_{21}\right) / \left(k_{2} / k_{3} \cdot \left(k_{3} + x_{3} + k_{6} \cdot \left(k_{18} - x_{3}\right)\right) + k_{19} + x_{9}\right)\right) / k_{17}\\
\frac{dx_{3}}{dt} = \left(1 \cdot k_{17} \cdot k_{18} / k_{9} + -1 \cdot k_{17} \cdot 1 / k_{9} \cdot x_{3} + -1 \cdot k_{17} \cdot x_{3} \cdot k_{7} \cdot k_{8} \cdot k_{19} \cdot k_{21} / \left(k_{1} + k_{21}\right) / \left(k_{3} / k_{2} \cdot \left(k_{2} + x_{9}\right) + x_{3} + k_{6} \cdot \left(k_{18} - x_{3}\right)\right)\right) / k_{17}\\
\frac{dx_{5}}{dt} = 0\\
\frac{dx_{7}}{dt} = 0\\
\frac{dx_{8}}{dt} = 0\\
\frac{dx_{11}}{dt} = 0