GATA6 and neoplasm: Five of seven PDAC cell lines with low levels of DKK1 mRNA expression had promoter methylation of DKK1, and four of these five also expressed low levels of GATA6, confirming the possibility that DKK1 epigenetic silencing occurs in a subset of PDACs that do not overexpress GATA6 as described for other tumor types [26], [33].