Although Igh7–/– mice showed an equivalent level of DNA-damage to WT following carcinogen exposure (Figure 3—figure supplement 1a), as assessed by staining for the phosphorylated histone H2A variant H2AX (γH2AX), only a few Igh7–/– mice developed tumours and the ones that did grew only very few and significantly smaller papillomas (Figure 3a), suggesting that the lack of IgE during TPA promotion hindered tumour growth. This evidence concerns the gene H2AX and neoplasm.