ATR and cancer: We gratefully acknowledge Roger Griffin, Celine Cano and Ian Hardcastle, Newcastle Cancer Centre – Medicinal Chemistry, Newcastle University for the provision of NU6027 and NU6252, Zdenek Hostomsky at Pfizer for the provision of PF-01367338, John Pollard at Vertex for assaying inhibition of ATR activity by NU6027 and Cancer Research UK (AP, L-ZW, ER, SK, TC, GB), UK National Health Service (RJE) and UK Higher Education Funding Council (NJC) for financial support.