IL6 and neoplasm: Detailed histological analysis showed that 26/28 (93%) Δ122/Δ122 IL-6+/+ mice (Fig. 2a), 8/9 (89%) of Δ122/Δ122 IL-6+/− mice (Fig. 2b) and 14/20 (70%) Δ122/Δ122 IL-6−/− mice (Fig. 2c) had developed malignant tumours at the time of death.