The distribution of the different laminin isoforms is tissue-specific. Laminin–111 is predominantly expressed in the embryonic epithelium, but can also be found in some adult epithelium such as the kidney, liver, testis, ovaries, and brain blood vessels. Different levels of expression of α chains have a large influence on the differential expression of laminin, thereby determining the isoform produced. From studying a mouse model, it was found that transcription factors present in the parietal endoderm regulate the expression of the α1 and large amounts of laminin-111 are produced.