PCSK9 and acute monocytic leukemia: In human acute monocytic leukemia cell line (THP-1) macrophages, PPD exerts a similar effect: it reduces the mRNA levels of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC) and promotes low-density lipoprotein (LDL) receptor expression by decreasing proprotein convertase subtilisin/kexin type 9 (PCSK9) levels [62].