Ara-C EC50 values plotted as a function of RNRi concentration in SAMHD1+/+, -/- and rescue (WT, H233A) THP-1 cell line pairs. EC50 values in the absence of RNRi are indicated by the black and red dotted line. Error bars indicate s.e.m. of two (HU and dF-dC) or three (3-AP) independent experiments, each performed in duplicate. 