CYP27B1 and periodontitis: Although CYP27B1 expressed in hGFs in vitro is the same as that in kidney, its regulation is different: periodontitis-related inflammatory stimuli interleukin-1β (IL-1β), sodium butyrate and Porphyromonas gingivalis lipopolysaccharide (Pg-LPS) induce significant up-regulation of CYP27B1, while regulators of 1 α-hydroxylase in kidney (parathyroid hormone, calcium and 1,25OH2D3) do not significantly influence the expression of CYP27B1 in hGFs in vitro (Gao, Liu & Meng, 2018; Liu, Meng & Hou, 2012b).