Using a syngeneic cell line (E0771) in female C57Bl/6 mice, Netherby‐Winslow et al. (2023) showed that serum IL‐1β and IL‐2 were elevated 4 weeks post‐tumour cell inoculation, and this correlated with a decrease in hippocampal neurogenesis (Netherby‐Winslow et al. 2023). This evidence concerns the gene IL2 and neoplasm.