Fig. 7. Quantitative analysis of tight junction protein profile length. Profile length was assessed in monolayers stained for the indicated TJ protein using well-oriented en face images at the plane of the TJ. Actual profile length was normalized to linear length (mean ± s.e.m.), as described in the Materials and Methods. tMLCK expression caused marked increases in ZO-1 and occludin profile length, consistent with the presence of many undulations. By contrast, claudin-1, claudin-2 and F-actin profile length were unchanged by tMLCK expression.