Deficient assembly and function of AP-3 complex. (A) Western blot analysis of fibroblast protein extracts showing decreased concentrations of AP-3 β, δ, and σ subunits. (B) Immunofluorescence analysis demonstrating deficiency of the δ subunit of the AP-3 complex in fibroblasts from patient no. 30 (right) compared with fibroblasts from a healthy control (left). (C) FACS analysis of fibroblasts stained for cell-surface expression of CD63 (LAMP3) revealed increased expression of CD63 on fibroblasts from patient no. 30 (red line) compared with control (green line). The mean fluorescence intensity (MFI) is indicated for the isotype control (gray), healthy donor, and patient no. 30.