ID1 and malignant colon neoplasm: Our findings are as follows: (i) sctive enhancer E1 located upstream of ID1 positively regulates ID1 expression; (ii) STAT3 up-regulates the expression of ID1 in part due to increasing enhancer activity and promoter-enhancer looping frequencies; (iii) enhancer E1 enhances the proliferation of colon cancer cells by regulating ID1 expression.