Reconstitution of licensing using purified proteins. a, c, d, Licensing activity of different combinations of purified proteins incubated in the presence of 2.5 mM ATP. DNA synthesis is expressed as % of the DNA template replicated. b, Western blot of Mcm7 loaded onto sperm chromatin in whole Xenopus extract, the full reconstituted reaction and the reconstituted reaction lacking RLF-B/Cdt1. The reconstituted reactions contained 2.5 mM ATP.