Although the mRNA levels of Glb1, mCherry, p16Ink4a and p21Wif1 were not much changed upon BLM treatment, protein levels of GLB1, p16Ink4a, p21Wif1 and mCherry were largely upregulated, as determined by RT-PCR, western blotting and IHC staining (Supplementary Fig. 12a–c). The gene discussed is GLB1; the disease is Bloom syndrome.