Finally, the recycled nutrients produced by autophagy in stromal cells provide a steady-stream of energy-rich metabolites (chemical building blocks) to cancer cells, inducing mitochondrial biogenesis, and protecting these "well-fed" cancer cells against apoptosis.
Thus, cancer cells induce oxidative stress in adjacent fibroblasts, 1) to generate recycled nutrients via autophagy, 2) to mutagenize themselves and evolve, and 3) to protect themselves against cell death (apoptosis).