The occurrence of apoptosis was assumed to be limited to metazoans, where elimination of single cells does not kill the whole organism. Nevertheless, recent studies revealed the existence of cell death pathway in yeast, Saccharomyces cerevisiae, and other unicellular eukaryotes, with typical hallmarks of apoptosis: DNA fragmentation, externalization of phosphatidyl serine and chromatin condensation. PCD in yeast is triggered by several different stimuli, including ageing, expression of mammalian pro-apoptotic proteins, exposure to low doses of H 2 O 2 , acetic acid, hyperosmotic stress and mating-type a-factor pheromone (9) (10) (11) . Unicellular organisms are believed to undergo PCD for a variety of reasons, including elimination of old, infected and damaged cells in growth-limiting conditions for better survival of the remaining population, and adaptation of the more fit subpopulation to the ever changing and challenging environment (12) . Orthologues of core regulators of mammalian apoptosis, such as the caspase-related protease Yca1, a homologue of mammalian pro-apoptotic mitochondrial serine protease HtrA2 (Nma111), a yeast EndoG nuclease Nuc1, apoptosis inducing factor (Aif1) involved in chromatin condensation, AIF-homologous mitochondrionassociated inducer of death (AMID) Ndi1 and an inhibitor of apoptosis (IAP) Bir1, are conserved in yeast (13) (14) (15) (16) (17) (18) . In addition, in both human and yeast cells, histone modifications (histone H2B phosphorylation at serine 14 in human and at serine 10 in yeast and H2B deacetylation at lysine 11 in yeast) play an important role in apoptotic chromatin condensation and cell death (19) (20) (21) . However, several apoptotic factors are missing in yeast, including the Bcl-2/Bax family and the apoptosis protease activator factor Apaf-1. Also, there is no good homologue of RNase L to execute possible RNA degradation. Nevertheless, yeast apoptosis has recently been shown to be activated in mRNA decay mutants (dcp and lsm) (22, 23) , supporting the notion that RNA metabolism and apoptosis are linked.