CHO pgsA-745 cells were electroporated with empty vector, an expression vector for wild-type human GPIHBP1, GPIHBP1-C65Y, GPIHBP1-Q115P, or GPIHBP1-G56R. 24 h later, the cells were incubated for 2 h at 4° C with human V5-tagged LPL with or without heparin (500 U/ml). At the end of the incubation, the cells were washed six times with ice-cold PBS, and cell extracts were prepared for western blotting. The amount of LPL bound to the cells was determined with a mouse monoclonal against the V5 tag; the levels of GPIHBP1 expression were assessed with a goat antibody against the S-protein tag. Actin was used as a loading control.