Effect of piperine on ABCA1 protein-dependent expression and the degradation rate of ABCA1 protein. (A) Differentiated THP-1 macrophages were incubated up to 24 h with (black circles) or without (solvent vehicle control; white circles) piperine at 50 µM. Cells were lysed at different time points (0, 3, 6, 15, 24 h) and proteins were resolved on SDS-PAGE. Immunodetection was performed with the indicated antibodies. All data are mean ± SD (n = 3) versus solvent vehicle control (DMSO), **p < 0.01; ***p < 0.001; n.s., no significance (two-way ANOVA/Bonferroni). (B) Differentiated THP-1 macrophages were incubated for 24 h with (black circle) or without (solvent vehicle control; white circle) piperine (50 µM) and lysed after addition of CHX (140 µM) at different time points (0, 10, 20, 40 min). Western blot analysis shows the decline of ABCA1 protein levels in the CHX-treated cells in the presence and absence of piperine. All data are mean ± SD (n = 3) versus solvent vehicle control (DMSO), **p < 0.01; n.s., no significance (two-way ANOVA/Bonferroni).