Fig. 5. Dynein-mediated MT sliding couples SPB translocation with spindle elongation. (a) Localization of dynein to MT plus ends depends upon Bik1p (CLIP-170) and Pac1p (LIS1). Bik1p build-up at MT plus ends requires the kinesin Kip2p. Dynein-bound MTs interact with the cortical anchor Num1p to generate pulling force by MT sliding independently of actin (b). Genetic analysis also implicates dynein and Bud6p in promotion of MT shrinkage at the cell cortex, although their role in a common pathway remains to be demonstrated.