SAMHD1 and cancer: As demonstrated previously (Hrecka et al, 2011; Laguette et al, 2011; Herold et al, 2017b), Vpx treatment efficiently depleted SAMHD1 protein (Fig 3C and E, Appendix Fig S10C) and, in line with our data in cancer cell lines, completely abolished the RNRi‐mediated sensitisation to ara‐C toxicity (Fig 3D and F).