Transcription of the murine laminin gamma 1 gene is activated during retinoic acid/cAMP induced differentiation of F9 embryonal carcinoma cells, Positive transcription control elements associated with two DNase I hypersensitive regions in the large first intron of the gene have been identified which confer a differentiation response on the laminin gamma 1 promoter, However, the kinetics of transcriptional activation suggest each DNA region interacts with transcription factors appearing at different times during differentiation, Synergy between the two regions in cis causes high level activation.