CENPV orthologs were detected in a range of species, including plants, but the proline-rich region was detected only in primates, rodents, birds, and amphibians, and long proline stretches were found only in primates. Northern blot analysis showed ubiquitous Cenpv expression in mouse tissues, with highest expression in testis, followed by small intestine, brain, and kidney. Immunofluorescence microscopy of mouse fibroblasts revealed colocalization of Cenpv with stabilized cytoplasmic microtubules. Western blot analysis of Ramos B cells detectedCENPV at an apparent molecular mass of 40 kD.