Microtubule plus-end tracking protein that promotes the stabilization of dynamic microtubules (By similarity). Operates redundantly with cls-2 and cls-3 in regulating microtubule processes which position the spindle during asymmetric cell division. No visible phenotype; due to the redundancy with cls-2 and cls-3. Simultaneous RNAi knockdown with cls-2 produces defective microtubule cortical contacts resulting in abnormal nuclear rotation, defects in maintenance of spindle length and spindle displacement. Simultaneous RNAi knockdown with cls-2 and cls-3 shows nuclear rotation defects and excessive spindle displacement. Belongs to the CLASP family.