ENPP1 and Hutchinson-Gilford progeria syndrome: Up-regulation of SPP1 in LMNAK542/K542N fibroblasts was detected by both microarrays and TaqMan expression assay (fold change of 2.7, p = 0.0026, and of 14.2, p = 0061, respectively), thus further confirming the correlation of increased ENPP1 expression levels with an unremarkable cardiovascular status in hereditary HGPS.