On the contrary, the fact that Wa1F1-KT was active only on C. albicans DSY289 implies that the mechanism of action of the toxin may be dependent upon the specific mutations that confer resistance to fluconazole in this strain. C. albicans DSY289 was derived from the fluconazole-susceptible clinical strain DSY347 by mutations that confer combined resistance to azoles . In particular, the point mutations S405F/Y132H in the ERG11 gene encoding the enzyme lanosterol 14-α-sterol demethylase, which is involved in converting lanosterol into ergosterol, an essential component of the fungal cell membrane, are associated with a conformational change of the target enzyme and reduced interaction or binding of azoles . The gain-of-function A736V mutation in the transcriptional activator TAC1 causes the overexpression of the ATP binding cassette (ABC)-transporters CDR1 and CDR2, decreasing the concentration of azoles within the fungal cell . It is not clear how this mutation may affect Wa1F1-KT activity, but it may be speculated that the overexpression of transport systems and associated extracellular loops could possibly alter the recognition of the cell surface target by the toxin or that the transcriptional activator TAC1 is involved in the regulation of transcription of toxin receptors.