PCSK9 and Pseudoxanthoma elasticum: Gene expression analysis of PCSK9 by RT2 Profiler PCR Array revealed a 46-fold increase in PXE fibroblasts compared to healthy controls grown under serum-free conditions (see section RT2 Profiler PCR Array).Verification by further qPCR showed significantly elevated mRNA expression in PXE fibroblasts for all cell culture settings in comparison to controls (Figure 6a: +10% FCS: 2.0-fold; +10% LDPS: 2.2-fold; −FCS: 4.1-fold).