Fig. 1

Roles of CAFs in tumorigenesis. Tumour cells and the surrounding fibroblasts or CAFs communicate to generate a microenvironment that either promotes or suppresses tumorigenesis. Normal fibroblasts can be stimulated to become CAFs by the tumour, however, the biological programmes that determine their skew towards a tumour-promoting or tumour-suppressing subtype remain unknown. The tumour-promoting subtypes aid tumour growth, survival and spread both directly and indirectly, through other tumour-associated stromal cell types. Both normal fibroblasts and CAFs have been shown to inhibit or retard tumorigenesis, but the mechanisms are relatively unknown