MRT00033659 is an effective broad-spectrum kinase inhibitor of CK1 (IC50=0.9 µM for CK1δ) and CHK1 (IC50=0.23 µM). MRT00033659 is a pyrazolo-pyridine analogue. It also induces p53 pathway activation and E2F-1 destabilization.
SB-218078 is less potently inhibits Cdc2 (IC50: 250 nM) and PKC (IC50: 1000 nM). SB-218078 is a potent, ATP-competitive, and cell-permeable checkpoint kinase 1 inhibitor that inhibits Chk1 phosphorylation of cdc25C (IC50: 15 nM).