In contrast to glycerol, lactate is taken up in the cells through a specific permease called Jen1 that also transports pyruvate (Casal, 1999; reviewed in Casal, 2008). JEN1 expression is repressed in the presence of glucose and is induced by lactate. D-Lactate and L-lactate are metabolized to pyruvate by two distinct mitochondrial lactate cytochrome c oxidoreductases, encoded by the DLD1 and CYB2 genes, respectively (Lodi & Ferrero, 1999). Unlike glycerol or lactate, ethanol and acetate are thought to enter the cells by passive diffusion, although an acetate carrier has been identified (Casal, 1996) (Fig. 1). Ethanol is also produced routinely in the cell as a consequence of alcoholic fermentation. Following its uptake, ethanol is metabolized to acetaldehyde by alcohol dehydrogenase (encoded by ADH2) and to acetate by aldehyde dehydrogenase (ALD6). Acetate is then transformed to acetyl-CoA by acetyl-CoA synthetase (ACS1).