Survival was markedly increased (Fig. 2a, P>0.0001, with survival in groups compared using the Log-Rank test) and tumour size markedly decreased (Fig. 2b) in Col5a3−/−, compared with WT, mice injected with WT/PyMT cells, indicating non-cell-autonomous contributions from microenvironments of stromal origin. This evidence concerns the gene COL5A3 and neoplasm.