Depression has been linked to (lack of) sunlight exposure and raised intracellular calcium levels. In this pathway, the role of the vitamin D pathway in calcium signaling in depression is shown. Active 1,25-dihydroxy-vitamin D3 is formed from 7-dehydrocholesterol by multiple conversion steps. It associates with RXR and VDR in the nucleus, which stimulates transcription of VDR target genes, resulting in lower intracellular calcium levels. Less sunlight exposure results in lower 1,25-dihydroxyvitamin D3 levels and therefore higher calcium levels.