Transcription factor that acts as the central regulator of the MDR1 efflux pump. Other target genes include those encoding oxidoreductases, whose up-regulation in fluconazole-resistant isolates may help to prevent cell damage resulting from the generation of toxic molecules in the presence of fluconazole and thereby contribute to drug resistance. Expression is coordinately up-regulated with MDR1 in drug-resistant, clinical isolates. Expression is induced by HAP43. Decreases MDR1 expression and leads to greater fluconazole and cerulenin susceptibility.