Vitamin D deficiency enhanced lung metastasis in vivo and markers of epithelial‐mesenchymal transition (EMT) in vitro. Mechanisms identified included co‐localization of chemokine CXCL12 and its receptor CXCR4 in the lung metastatic niche and increased expression of pSTAT3 and ZEB1 (EMT drivers). This evidence concerns the gene CXCL12 and vitamin D deficiency.