Figure 7.

Inhibition of MAPK/ERKs in Δ15 PECAM-1–expressing cells restores E-cadherin expression and junctional localization of PECAM-1. MDCK cells (2 × 10⁴) expressing the Δ15 PECAM-1 isoform were plated on glass coverslips and incubated with medium containing PD98059 (50 μM) for 4 d. Cells were fixed and stained with antibodies to E-cadherin (A and B) or PECAM-1 (C and D) as described in MATERIALS AND METHODS. The localization of E-cadherin and PECAM-1 was examined by indirect immunofluorescence (40× objective). Two different clones of MDCK Δ15 PECAM-1 were used (A and C, clone 19; B and D, clone 36). Note the reexpression and localization of E-cadherin at sites of cell–cell contact (A and B). Δ15 PECAM-1 isoform now also exhibits a junctional localization. Cells incubated with the vehicle alone for the duration of the experiments showed no effect on morphology and/or the expression of E-cadherin and PECAM-1 (our unpublished results).