Transcription of the iso-2 cytochrome c gene of Saccharomyces cerevisiae (CYC7) is strongly induced by stationary-growth phase, heat shock and low cAMP levels. CYC1, the iso-1 cytochrome c gene, is strongly repressed in stationary phase and unaffected by heat shock and cAMP levels. Heat shock-induced transcription of CYC7 occurs both aerobically (4-6 fold) and anaerobically (30 fold).