a, Experimental design to induce host mice with conditional whole-body deletion of Atg5 (Atg5Δ/Δ) and wild-type controls (Atg5+/+) with which to assess tumour growth. Ubc-creERT2/+;Atg5+/+ and Ubc-creERT2/+;Atg5flox/flox mice were injected with TAM at 8 to 10 weeks of age to delete Atg5 and create Atg5+/+ and Atg5Δ/Δ hosts. Mice were then injected subcutaneously with tumour cells and tumour growth was monitored over three weeks. b, Comparison of tumour weight between Atg5+/+ (n = 4) and Atg5Δ/Δ (n = 3) hosts. Data are mean ± s.e.m. **P < 0.01. c, Immunohistochemistry quantification of Ki-67+ and active caspase-3+ cells in tumours from Atg5+/+ and Atg5Δ/Δ hosts. Data are mean ± s.e.m. ****P < 0.0001. d, Western blotting showing expression of ARG1 in serum from Atg5+/+ (n = 3), Atg5Δ/Δ (n = 4) and Atg7Δ/Δ (n = 3) hosts. *P < 0.05 compared to Atg5+/+ hosts. Transferrin was used as a loading control. e, Levels of arginine, ornithine and citrulline in serum in Atg5+/+ (n = 4) and Atg5Δ/Δ (n = 3) hosts, obtained by LC–MS. Data are mean ± s.e.m. *P < 0.05, **P < 0.01.