(A) Structures of 7-azaindole-3-carbonitrile hit fragment, BD8900 and BDP9066. (B) BDP8900 dose-response curves for inhibition of MRCKα, MRCKβ, ROCK1 and ROCK2 kinase activity in vitro at 1 µM ATP. (C) BDP9066 dose-response curves for inhibition of MRCKα, MRCKβ, ROCK1 and ROCK2 kinase activity in vitro at 1 µM ATP. Results shown are mean ± SD of duplicate independent replicates. (D) Cells expressing doxycycline-induced MRCKβ, ROCK1 or ROCK2 kinase domains were treated with BDP8900 at indicated concentrations for 60 minutes prior to lysis and quantitative western blotting. Inhibition of MLC2 phosphorylation by BDP8900 for each induced kinase domain. Results shown are mean ± SEM of 3-4 independent replicates. (E) Cells expressing doxycycline-induced MRCKβ, ROCK1 or ROCK2 kinase domains were treated with BDP9066 at indicated concentrations for 60 minutes prior to lysis and quantitative western blotting. Inhibition of MLC2 phosphorylation by BDP8900 for each induced kinase domain. Results shown are mean ± SEM of 3-4 independent replicates.