TLDR Mice without the vitamin D receptor are more prone to UV-induced skin tumors.
The study concluded that inactivation of the Vitamin D Receptor (VDR) in mice increased their susceptibility to UV-induced skin tumorigenesis. VDR−/− mice developed skin tumors more rapidly and frequently than wildtype controls, showing compromised DNA repair, defective UV-induced growth arrest and apoptosis, and reduced epidermal thickening in response to UV exposure. These findings highlighted the critical protective role of VDR in preventing UV-induced skin damage and tumor formation, independent of its ligand, 1,25(OH)2D3. The study involved various groups of mice with sample sizes ranging from 6 to 23 per group.
36 citations,
February 2007 in “Journal of biological chemistry/The Journal of biological chemistry” The vitamin D receptor can work without its usual activating molecule.
140 citations,
April 2004 in “The journal of investigative dermatology/Journal of investigative dermatology” The enzyme 25 Hydroxyvitamin D 1 α-Hydroxylase is essential for healthy skin and recovery after skin damage.
277 citations,
July 2002 in “Molecular Endocrinology” Removing part of the vitamin D receptor stops vitamin D from working properly.
18 citations,
July 2010 in “Journal of steroid biochemistry and molecular biology/The Journal of steroid biochemistry and molecular biology” The vitamin D receptor helps regulate skin and hair health independently of its usual vitamin D ligand.
158 citations,
August 2011 in “Reviews in endocrine and metabolic disorders” Vitamin D and its receptor regulate skin functions like cell growth, immunity, hair cycle, and tumor prevention.
120 citations,
February 2009 in “Apoptosis” Understanding how cells die in the skin is important for treating skin diseases and preventing hair loss.
76 citations,
January 2010 in “Journal of bone and mineral metabolism” 
185 citations,
December 2011 in “Molecular and cellular endocrinology” Skin cells produce and activate vitamin D, which regulates skin functions and supports hair growth.
