GST-PFO labels vesicles containing DiI-LDL in NPC cells. NPC fibroblasts (A-A”) and healthy control fibroblasts (B-B”) were cultured in DMEM supplemented with delipidated 10% FBS for 72 h, incubated with 10 μg/ml DiI-LDL for 5 h and, after fixation and permeabilization, processed for GST-PFO labeling. (A, B) GST-PFO staining, (A’, B’) fluorescence of DiI-LDL, (A”, B”) merged images. Inset in (A”) shows an enlargement of a marked area. Scale bar, 20 μm.