We previously identified cancer-upregulated gene 2 (CUG2) as a commonly up-regulated gene in various human cancer tissues, especially in ovary, liver, and lung (Lee et al., 2007a). CUG2 was determined to be a nuclear protein that exhibited high proto-oncogenic activities when overexpressed in NIH3T3 mouse fibroblast cells. To identify other cellular functions of CUG2, we performed yeast two-hybrid screening and identified CENP-T, a component of CENP-A nucleosome complex in the centromere, as an interacting partner of CUG2. Moreover, CENP-A, the principle centromeric determinant, was also found in complex with CENP-T/CUG2. Immunofluorescent staining revealed the co-localization of CUG2 with human centromeric markers. Inhibition of CUG2 expression drastically affected cell viability by inducing aberrant cell division. We propose that CUG2 is a new component of the human centromeric complex that is required for proper chromosome segregation during mitosis.