Fig. 2.

Interaction diagram of our model. Stroma inhibits tumour cell proliferation but is killed by acid secreted by the acid producing tumour cells, $T_{\mathrm{A}}$. In contrast, tumour cells ($T_{\mathrm{A}}$ and $T_{\mathrm{M}}$) are assumed to be resilient to acid. ECM blocks movement of the tumour cells, but can be removed by the matrix-degrading tumour cells, $T_{\mathrm{M}}$. The two types of tumour cells compete for resources thereby inhibiting each other’s growth (Color figure online)