Provides structural support to stabilize and organize the microtubule spindle during mitosis (within embryonic somatic cells) and meiosis (within spermatocytes). The role in mitosis regulation depends on the Ran pathway. Interacts with Chro and Mtor as part of a macromolecular complex forming the spindle matrix. Chro colocalizes with Skeletor on the chromosomes at interphase and on spindle during metaphase. Part of a macromolecular complex forming the spindle matrix. During mitosis, associated with chromatin at interphase, redistributes to the spindle structure at prophase (preceding the formation of the microtubule spindle) through to anaphase. Extends from one end of the spindle to the other during metaphase and anaphase, coaligns with the microtubule spindle. Isoform D is expressed during embryonic development. Intron retention. Intron retention.