This study explored the role of clusterin in mechanisms of cell adhesion and apoptosis in P19 embryonic carcinoma cells. We found that serum deprivation induced transient but dramatic elevation in cell adhesion strength to the culture substrate and eventually led to apoptotic cell death. The time course of cell-adhesion increase overlapped temporally with the elevation of clusterin mRNA (peak 8 h after serum deprivation). The coincidental elevation of clusterin expression and cell adhesion strength preceded the schedule of apoptotic cell death. Clusterin antiserum partially antagonized cell adhesion, but did not modify the course of apoptosis. These data suggest that clusterin expression may partially control cell adhesion with no influence on apoptosis in P19 cells, under defined conditions.