Table 1.

Potent and specific small molecule inhibitors of ATR and CHK1.

CHK1 Inhibitors
Name	Structure	IC50/Ki	Specificity
AZD7762		CHK1 IC50 = 5 nM	Equally potent: CHK1/CHK2
V158411		CHK1 IC50 = 4.4 nM	Equally potent: CHK1/CHK2; 20-fold CHK1 vs. CHK2 in cells (Cellular CHK1 IC50 = 48 nM vs. CHK2 IC50 = 904 nM)
PF477736		CHK1 Ki = 4.9 nM	100-fold CHK1 vs. CHK2
MK8776/SCH900776		CHK1 IC50 = 3 nM	500-fold CHK1 vs. CHK2
CCT244747		CHK1 IC50 = 8 nM	>1000-fold CHK1 vs. CHK2
CCT245737		CHK1 IC50 = 1.3 nM	>1500-fold CHK1 vs. CHK2
LY2603618		CHK1 IC50 = 7 nM	>1500-fold CHK1 vs. CHK2
ATR Inhibitors
Name	Structure	IC50/Ki	Specificity
NU6027		ATR IC50 = 1 nM	ATR, CDK1 (Ki = 2.5 µM), CDK2 (Ki = 1.3 µM)
ETP-46464		ATR IC50 = 25 nM	ATR
VE-821		ATR IC50 = 26 nM	>100-fold ATR vs. ATM/DNA-PK
VE-822/VX-970		ATR IC50 = 0.2 nM	>100-fold ATR vs. ATM/DNA-PK
AZ20		ATR IC50 = 5 nM	>600-fold ATR vs. ATM/DNA-PK/PI-3K
AZD6738		ATR IC50 = 1 nM	ATR