DKK1 and neoplasm: For example, smoking-induced repression of miR-487b -a tumor suppressor miRNA that normally inhibits Wnt5a, Myc, and Kras and upregulates the Wnt antagonists Dkk1, Sfrp1, Sfrp4, and Wif1 to regulate lung stem cells- results in increased proliferation, invasion and metastatic potential of lung cancer cells (Xi et al., 2013).