Stathmin expression is associated with the ability of cells to progress through the cell cycle

Stathmin is a prominent cytosolic protein which can be phosphorylated by MAP kinase, cAMP-dependent protein kinase and p34^cdc2 kinase. Iinmunoslaining of human and mouse tissues has revealed that stathmin is expressed in the proliferative compartment of cells of most, if not all, eel! lineages. The myeloid cell lines HL60 and K562 express stathmin at very high levels. When these cells are induced to differentiate, stathmin expression is down-regulated as cells go out of cycle. A decrease in the proportion of stathmin that is phosphorylated was also observed. To investigate the role that stathmin plays in the control of cell proliferation, we have transfected the promonocytoid cell line U937 with the pMep4 vector containing stathmin cDNA in an antisense orientation. Antisense stathmin transfected cells were unable to undergo normal cell division and became multinucleate. Belmont and Mitchison (Cell 19%, 84, 623-631) have shown in vitro that stathmin interacts with tubulin dimers to increase the catastrophe rate of microtubules and suggest that stathmin may increase the catastrophe rate of microtubules during mitosis. The above findings show that stathmin plays an important role in the progression of cells through cycle.