The lipoproteins were pre-labeled with dipalmitoyl [14C] PC, and an aliquot of the labeled lipoprotein was subjected to SMase treatment as described in the text. The SMase-treated and untreated lipoproteins were then incubated with recombinant HL (500 μl, 32 μg protein) for the indicated periods of time at 37 °C. The lipids were extracted, and the radioactivity in LPC, PC, and FFA was determined following their TLC separation. The results show the decrease in PC counts (%) compared to the control (incubated with no HL), and are mean ± SEM of 4 experiments. * p < 0.01 HL vs HL + SMase.