MRT68921 is a potent and dual autophagy kinase ULK1/2 inhibitor with IC50 of 2.9 nM and 1.1 nM, respectively.

ULK2:1.1 nM, ULK1:2.9 nM

MRT68921 specifically disrupts autophagosome maturation and thus blocks autophagic flux through ULK1 inhibition. [1]

Kinase assays are carried out in 50 mM Tris-HCl, pH 7.4, 10 mM magnesium acetate, 0.1 mM EGTA, and 0.1% β-mercaptoethanol, containing 30 μM cold ATP, and 0.5 μCi of [γ-32P]ATP for 5 min at 25 °C. Prior to ATP addition, reaction mixes are pre-warmed to 25 °C for 5 min. Reactions are stopped by the addition of sample buffer, followed by SDS-PAGE, transfer to nitrocellulose, and analysis by autoradiography and immunoblot[1].

MEFs and 293T cells are grown in DMEM, supplemented with 10% fetal bovine serum and penicillin/streptomycin, and cultured at 37°C, 5% CO2. For induction of autophagy, cells are typically grown to 75% confluency, ished twice, and incubated in Earle's balanced salt solution (EBSS) for 1 h (or complete medium as a control). MRT67307 (10 μM), MRT68921 (1 μM), AZD8055 (1 μM), or bafilomycin A1 (50 nM) is included[1].