This study investigates tissue-specific in vitro transcription from the mouse albumin promoter using nuclear extracts from rat liver, brain, and spleen. The adenovirus-2 major late promoter is active in all extracts, but the mouse albumin promoter is significantly active only in the liver extract. The sequences between -170 and -55 are essential for liver-specific transcription, as deleting this region results in a 100-fold reduction in transcription. Inserting these sequences upstream of the parotid-specific Amy1 promoter increases its activity to levels comparable to the albumin promoter. The study also demonstrates that the tissue-specific transcription from the albumin promoter is controlled by positive transcription factors present in the liver extract, as the activity of the liver extract is not repressed by the brain extract. These findings suggest that the in vitro transcription system can be a valuable tool for identifying and characterizing tissue-specific transcription factors.This study investigates tissue-specific in vitro transcription from the mouse albumin promoter using nuclear extracts from rat liver, brain, and spleen. The adenovirus-2 major late promoter is active in all extracts, but the mouse albumin promoter is significantly active only in the liver extract. The sequences between -170 and -55 are essential for liver-specific transcription, as deleting this region results in a 100-fold reduction in transcription. Inserting these sequences upstream of the parotid-specific Amy1 promoter increases its activity to levels comparable to the albumin promoter. The study also demonstrates that the tissue-specific transcription from the albumin promoter is controlled by positive transcription factors present in the liver extract, as the activity of the liver extract is not repressed by the brain extract. These findings suggest that the in vitro transcription system can be a valuable tool for identifying and characterizing tissue-specific transcription factors.