Microtubule-associated force-producing protein that plays a role in organelle transport. Its motor activity is directed toward the microtubule's plus end. The maximal velocity in an inverted motility assay (moving microtubules on fixed motors) was 1.96 um/s. {ECO:0000269|PubMed:10545495; ECO:0000269|PubMed:18160177}.