Centrosomes are dynamic organelles involved in many aspects of cell function and growth. Centrosomes act as microtubule organizing centers, and provide a site for concerted regulation of cell cycle progression. Duplication of centrosomes occurs once during each cell cycle and requires proper mitotic spindle formation and chromosome segregation. Defects in centrosome duplication or function are linked to many human diseases, including various forms of cancer. The centrosome and spindle pole-associated protein 1 (CSPP1) interacts with centrosomes and microtubules and may play a role in the regulation of G(1)/S-phase progression and spindle assembly. Two isoforms of CSPP1 exist as a result of alternative splicing events. Isoform 1 expression increases throughout the cell cycle and peaks in G2/M phase, whereas isoform 2 expression is highest in G1 phase and decreases thereafter.