Permeability effect of CD is mediated by an M6P-dependent mechanism. A) ECIS tracings of HRECs treated with CD beads, CD beads with 20 μM PepA, CD beads with 50 μM PepA, or Ctrl. *P = 0.001, significantly less than cells grown in Ctrl. B) ECIS tracings of HRECs treated with CD beads, CD beads plus 100 μM M6P, or Ctrl. *P = 0.02, significantly less than cells treated with CD beads alone.