Dynasore Impairs Cholesterol Homeostasis Figure 11. U18666A inhibits ACAT activity and sterol-sensitive genes regulation in HeLa cells and HMDM. Cells were grown in LPDS medium for 48 h and further incubated for 6 h with 200 mg/ml LDL (A) or 50 mg/ml AcLDL (B) with 3 mg/ml U18666A or without (control). Relative quantification of LDLR, HMGCoAR, and SREBF-2 genes in HeLa cells (A) or HMDM (B) was expressed as fold-variation over control (LPDS/DMSO) after normalization. All CT determinations were made in triplicate. The total amount of CE was quantified HeLa cells (C) and in HMDM (D) and expressed as the percent of the total amount of cholesterol. ACAT-dependent ester formation was measured with 10 mg/ml ACAT inhibitor (grey bars). Cholesteryl myristate formation was measured in HeLa cells (E) or HMDM (F) with 3 mg/ml U18666A or without (control). Cholesteryl myristate was expressed in nmol/mg protein. Each value is the mean of triplicate experiments. doi:10.1371/journal.pone.0029042.g011 FC to the ER by alternative pathways has to be documented. In this context, it is interesting that the inhibition of LDL uptake by dynasore persisted for 24 hours suggesting that the drug was still active at this time (data not shown). Different cholesterol efflux pathways have been described that occur either by a non regulated diffusive process, or actively mediated by SR-BI and ABC transporters [26]. Recent studies indicate that ABCA1 and ABCG1 are the main contributors to the PLoS ONE | www.plosone.org 11 December 2011 | Volume 6 | Issue 12 | e29042