cloning and characterization of 5untranslated region of porcine beta casein gene csn2 betacasein csn2 is a major milk protein in most mammals the csn2 gene is generally induced by lactogenic hormones bound to its promoter the expression of this gene can be enhanced by signal transducers and activators of transcription stat and glucocorticoid receptor gr here we analyzed the promoter and intron 1 regions of the porcine csn2 gene the porcine csn2 promoter and intron 1 regions 3098bp to 2446bp were cloned into the pgl3basic vector containing the luciferase reporter gene pcsn2pei lactogenic signals induced the transcription of porcine csn2 by using ag490 a janus kinase jak inhibitor we demonstrated that stat5 positively regulates the transcription of porcine csn2 further seven stat mutants were generated by sitedirected mutagenesis by performing electrophoretic mobility shift assays emsas we located a critical element for pcsn2pei transcription bound to stat5 in the 102bp to 84bp region the construct containing only the promoter region pcsn2p however did not exert any promotive effects on transcription in two cell typesa mouse mammary epithelial cell line hc11 and porcine mammary gland epithelial cells pmecs thus the construct containing intron 1 of porcine csn2 exerts an elevating effect on transcription we suggest that the transcription of porcine csn2 is regulated by lactogenic signals via the stat5 site 102bp to 84bp and intron 1