Importantly, our data imply cell type specificity of HELLS function, suggesting that highly proliferating cancer cells with elevated HELLS expression might rely on HELLS for SSB repair, whereas HELLS might be dispensable in slowly proliferating, non-transformed cells with low HELLS expression (Figs 1A–F, 2A, Supplementary Fig. S1A–C, G–I). Here, HELLS is linked to cancer.