Our previous investigations showed that Smg1gt/+ mice had elevated levels of tissue and serum cytokines prior to the onset of disease.12 Furthermore, loss of ATM can result in increased inflammation due to unrepaired DNA damage resulting in an accumulation of cytosolic DNA and subsequent pro‐inflammatory cytokine production.5, 17 As an inflammatory microenvironment may also contribute to the development of haematopoietic tumours, we determined cytokine levels in Atm−/−Smg1gt/+ mice. This evidence concerns the gene ATM and hematopoietic and lymphoid cell neoplasm.