Proliferating human cells express mitochondrial VDR, whereas differentiated cells display reduced levels of receptor expression.

<p>(<b>A</b>) VDR expression was analyzed in a panel of several human cell lines using western blotting in total lysates (tot VDR) and mitochondrial extracts (mitoc VDR). For RD and MCF7 cells, VDR detection required a longer duration of exposure to ECL. (<b>B</b>) Two models of cellular differentiation were used to assess VDR levels in the total lysates and mitochondrial fractions: Human proliferating HaCaT cells vs. human primary differentiated keratinocytes and differentiation-inducible RD18 cells carrying a doxycycline-inducible miR-206-expressing lentiviral vector in the absence (uninduced: NI) or presence of doxycycline for four (induced: IND4) and six days (induced: IND6). Tubulin detected in total extracts and VDAC levels in mitochondrial fractions were used as internal controls for protein loading. The blots are representative of a set of three independent experiments.