After longer BLM treatment (3 h), the immunostaining assay revealed that, in contrast to the largely dispersed distribution under mock condition (Supplementary Fig. 6), the XIP signals became focused and co-localized well with all the observed BLM-induced γ-H2A.X foci in DAPI-stained nuclei, although with a slight diffusion around (Fig. 1e). Here, LAMTOR5 is linked to Bloom syndrome.