The present invention provides an expression cassette comprising (1) an expression regulatory region having a sequence corresponding to a transcriptional activator-binding region and (2) a nucleic acid encoding a transcriptional activator which is capable of binding to the expression regulatory region, wherein the nucleic acid is operably linked to the expression regulatory region; a method for expressing a target product in a mammalian cell, a method for producing a cell expressing a target product, and a method for producing a target product in a mammalian cell using the expression cassette; and a kit comprising the expression cassette.