Figure 5. Diagrammatic representation of the inner inert and outer proliferating shell structure of the Evans (2014) model used to represent the structure of a tumor.

The proliferating outer shell consists of the cycling cell cycle model and the inner core represents the cell cycle model where progression through the cell cycle is halted. Inhibition of repair by addition of AZD6738 promotes cell death, thereby depleting the outer proliferating shell which is replaced by cells from the inert inner core, reducing the total tumor volume.