$\begin{array}{l}\text{\hspace{0.05em}}+W\left({N}_{I+},{N}_{I-},{N}_{0}\to {N}_{I+}+1,{N}_{I-}-1,{N}_{0}\right)+W\left({N}_{I+},{N}_{I-},{N}_{0}\to {N}_{I+}-1,{N}_{I-}+1,{N}_{0}\right)\\ \text{\hspace{0.05em}}+W\left({N}_{II+},{N}_{II-},{N}_{0}\to {N}_{II+}+1,{N}_{II-}-1,{N}_{0}\right)+W\left({N}_{II+},{N}_{II-},{N}_{0}\to {N}_{II+}-1,{N}_{II-}+1,{N}_{0}\right)\}\\ \text{\hspace{0.05em}}\times P\left({N}_{I+},{N}_{I-},{N}_{II+},{N}_{II-},{N}_{0};t\right)\\ \text{\hspace{0.05em}}+W\left({N}_{I+}+1,{N}_{I-},{N}_{0}-1\to {N}_{I+},{N}_{I-},{N}_{0}\right)P\left({N}_{I+}+1,{N}_{I-},{N}_{II+},{N}_{II-},{N}_{0}-1;t\right)\\ \text{\hspace{0.05em}}+W\left({N}_{I+},{N}_{I-}+1,{N}_{0}-1\to {N}_{I+},{N}_{I-},{N}_{0}\right)P\left({N}_{I+},{N}_{I-}+1,{N}_{II+},{N}_{II-},{N}_{0}-1;t\right)\end{array}$

$\begin{array}{l}\text{\hspace{0.05em}}+W\left({N}_{I+}-1,{N}_{I-},{N}_{0}+1\to {N}_{I+},{N}_{I-},{N}_{0}\right)P\left({N}_{I+}-1,{N}_{I-},{N}_{II+},{N}_{II-},{N}_{0}+1;t\right)\\ \text{\hspace{0.05em}}+W\left({N}_{I+},{N}_{I-}-1,{N}_{0}+1\to {N}_{I+},{N}_{I-},{N}_{0}\right)P\left({N}_{I+},{N}_{I-}-1,{N}_{II+},{N}_{II-},{N}_{0}+1;t\right)\\ \text{\hspace{0.05em}}+W\left({N}_{II+}+1,{N}_{II-},{N}_{0}-1\to {N}_{II+},{N}_{II-},{N}_{0}\right)P\left({N}_{I+},{N}_{I-},{N}_{II+}+1,{N}_{II-},{N}_{0}-1;t\right)\\ \text{\hspace{0.05em}}+W\left({N}_{II+},{N}_{II-}+1,{N}_{0}-1\to {N}_{II+},{N}_{II-},{N}_{0}\right)P\left({N}_{I+}{N}_{I-},{N}_{II+},{N}_{II-}+1,{N}_{0}-1;t\right)\\ \text{\hspace{0.05em}}+W\left({N}_{II+}-1,{N}_{II-},{N}_{0}+1\to {N}_{II+},{N}_{II-},{N}_{0}\right)P\left({N}_{I+},{N}_{I-},{N}_{II+}-1,{N}_{II-},{N}_{0}+1;t\right)\end{array}$

$\begin{array}{l}\text{\hspace{0.05em}}+W\left({N}_{II+},{N}_{II-}-1,{N}_{0}+1\to {N}_{II+},{N}_{II-},{N}_{0}\right)P\left({N}_{I+},{N}_{I-},{N}_{II+},{N}_{II-}-1,{N}_{0}+1;t\right)\\ \text{\hspace{0.05em}}+W\left({N}_{I+}+1,{N}_{I-}-1,{N}_{0}\to {N}_{I+},{N}_{I-},{N}_{0}\right)P\left({N}_{I+}+1,{N}_{I-}-1,{N}_{II+},{N}_{II-},{N}_{0};t\right)\\ \text{\hspace{0.05em}}+W\left({N}_{I+}-1,{N}_{I-}+1,{N}_{0}\to {N}_{I+}{N}_{I-},{N}_{0}\right)P\left({N}_{I+}-1,{N}_{I-}+1,{N}_{II+},{N}_{II-},{N}_{0};t\right)\\ \text{\hspace{0.05em}}+W\left({N}_{II+}+1,{N}_{II-}-1,{N}_{0}\to {N}_{II+},{N}_{II-},{N}_{0}\right)P\left({N}_{I+},{N}_{I-},{N}_{II+}+1,{N}_{II-}-1,{N}_{0};t\right)\\ \text{\hspace{0.05em}}+W\left({N}_{II+}-1,{N}_{II-}+1,{N}_{0}\to {N}_{II+},{N}_{II-},{N}_{0}\right)P\left({N}_{I+},{N}_{I-},{N}_{II+}-1,{N}_{II-}+1,{N}_{0}:t\right)\end{array}$ (1)

Here, $W\left({N}_{I+},{N}_{I-},{N}_{0}\to {N}_{I+}+1,{N}_{I-},{N}_{0}-1\right)$ is the transition probability for an undifferentiated cell to change into +type in region I and the other transition probabilities W’s are also used by denoting the changes in parentheses. These transition probabilities on the right-hand side of Equation (1) are explicitly expressed by the first four, ninth and tenth, thirteenth to sixteenth, and twenty-first and twenty-second transition probabilities in the following way.