EGFR and neoplasm: In our model, however, we find that EGFR and PDGFRA amplified sub-populations can be found to coexist in areas of the tumour region despite actively competing with one another; we find that any E ̄, P ̄, N ̄≥0 satisfying E ̄+P ̄+N ̄=K is a spatially homogeneous steady state and can be connected to other spatially homogeneous steady states satisfying the same condition, or the trivial steady state E ̄=P ̄=N ̄=0, by travelling wave-like solutions expanding outwards from the origin of the tumour.