Regulation of dynein-driven microtubule sliding is disrupted in the mia mutants. ATP- and protease-induced microtubule sliding measurements show the characteristic sliding velocities for wild-type (wt) and pf17 mutant axonemes. The reduced sliding velocity of pf17 is rescued to wild-type levels by the addition of a kinase inhibitor (KI). Microtubule sliding velocities of mia1 (mia1-1 and mia1-3) are similar or only slightly reduced relative to that of wild type but greatly reduced when coupled with the pf17 mutation (mia1-1 × pf17). Microtubule sliding velocities of mia2 axonemes are significantly reduced and are not altered by kinase inhibitor treatment (mia2 + kinase inhibitor). Error bars show standard deviations (n = 4–36).