Fig 2: iPSC-derived BMEC marker and retinoid-related protein validation by immunocytochemistry and Western blot.A) Expression of endothelial cell marker PECAM-1; tight junction and associated proteins CLDN5, OCLN and TJP1 (ZO-1); glucose transporter SLC2A1 (GLUT1). Proteins are labeled in green and nuclear stain in blue. Scale bar equals 100 µm. B) Expression of efflux transporters ABCG2 (BCRP), ABCC1 (MRP1) and retinoid-related proteins STRA6, CRBP1 and LRAT. Proteins are labeled in green and nuclear stain in blue. Scale bars equal 100 µm. C) Western blots of CRBP1 (red), LRAT (red), and STRA6 (red) confirming antibody specificity. An antibody against TJP1 (green) is used as a BMEC specific loading control in each blot. Polyclonal STRA6 antibody was additionally validated against recombinant GST-tagged STRA6.