GH1 and adenoma: Decreased expression of E‐cadherin in pituitary (including GH‐producing) adenomas has been previously reported.14, 17, 18, 19, 20 However, the association between the loss of E‐cadherin expression and aggressiveness of GH‐producing tumours has yielded conflicting results.14, 17, 18, 19, 20 E‐cadherin expression levels are also correlated with GH‐producing tumour histological subtypes.