Selumetinib is a potent, highly selective MEK1 inhibitor with IC50 of 14 nM, also inhibits ERK1/2 phosphorylation with IC50 of 10 nM, no inhibition to p38α, MKK6, EGFR, ErbB2, ERK2, B-Raf, etc.

Trametinib is a highly specific and potent MEK1/2 inhibitor with IC50 of 0.92 nM/1.8 nM, no inhibition of the kinase activities of c-Raf, B-Raf, ERK1/2.

U0126 ethanol is a highly selective inhibitor of MEK1/2 with IC50 of 0.07 μM/0.06 μM.

CI-1040 is an ATP non-competitive MEK1/2 inhibitor with IC50 of 17 nM, being 100-fold selective for MEK1/2 than MEK5.

SL327 is a cell-permeable vinylogous cyanamide that acts as a selective inhibitor of MEK-1 and MEK-2 (IC50 = 0.18 and 0.22 μM respectively).

Refametinib is a specific and non-ATP-competitive MEK 1/2 inhibitor with IC50 values of 19 and 47 nM, respectively.

BI-847325 is a selective and orally bioavailable dual MEK/Aurora kinase inhibitor with IC50 of 3 nM (Xenopus laevis Aurora B), 25 nM (human Aurora A), 15 nM (human Aurora C), 25 nM (human MEK1), and 4 nM (human MEK2) respectively.