Abstract: Described herein is a method for producing a transgenic cell product wherein the gene of interest is operably linked to an inducible promoter other than AOX1. Production of the transgenic cell product is activated when the host cell is grown on a non-repressing carbon source for de-repressing the inducible promoter and an amount of an inducer compound selected from the group consisting of: formaldehyde; S-formylglutathione; S-hydroxymethyl glutathione; formic acid; an alkali metal salt of formic acid; and an alkaline earth metal salt of formic acid; sufficient to induce the inducible promoter is added to the host cell culture.