APP and Alzheimer disease: miR-106b, miR-20a, miR-17-5p expression decreased in AD brains; overexpression of miR-106b, miR-20a, miR-17-5p affected relative luciferase expression cloned with APP. Overexpression of miR-106b, miR-20a, miR-17-5p could repress APP protein level. The reduction of miR-20a, miR-17-5p and miR-106b during brain development in mouse is well correlated with the upregulation of APP protein levels; the correlation between APP and miR-20a, miR-17-5p, and miR-106b also confirmed in these cells.