Spearman correlation of relative SAMHD1 protein abundance and synergy delta scores for ara-C versus HU or dF-dC in a panel (n = 9) of haematological cancer cell lines. Error bars indicate s.e.m. Each data point corresponds to SAMHD1 protein levels determined by immunoblot analysis (n = 4 for each cell line, representative blot shown in Appendix Fig S2) and an average delta score from repeated dose-response matrix experiments each performed in triplicate: THP-1, n =4; HuT-78, n = 2; HL-60/iva, n = 1; KBM-7, n = 2 (HU) and 3 (dF-dC); K562, n = 3 (HU) and 4 (dF-dC); CCRF-CEM, n =3 (HU) and 4 (dF-dC); MV-4-11, n = 2 (HU) and 3 (dF-dC); Jurkat, n = 2 (HU) and 3 (dF-dC); MOLT-4, n = 2 (HU) an 3 (dF-dC). 