To access the data, click or select the words “Appendix 2.” Comparative immunohistochemical analysis of expression and distribution of fibronectin (an EMT marker) and occludin in control (DYS) and A2 SLOS iPSC-derived RPE cells. Occludin (green), fibronectin (red), and F-actin (Alexa Fluor 568-conjugated phalloidin, pseudocolored gray) in DYS (upper panels) and A2 (lower panels) RPE cells. DYS RPE cells formed a continuous, relatively uniform polygonal monolayer with predominantly occludin-positive tight junctions at the cell borders (red arrows), with no obvious fibronectin expression, and a circumferential pattern of F-actin (yellow arrows). By contrast, A2 RPE cells formed a heterogeneous monolayer, with regional occludin immunolabeling of tight junctions along polygonal cell borders (red arrow), but also some regions devoid of occludin at the tight junctions (yellow asterisk). Elevated fibronectin expression in regions exhibiting poor occludin immunolabeling of the cell borders was observed in A2 RPE cells (yellow asterisk). Regional F-actin stress fiber formation was evident in A2 RPE cell monolayers, especially in areas undergoing EMT (yellow arrows). Scale bar (all panels): 20 µm.