secretory pathway secretory pathway Secretory pathway transported towards the cell membrane secretory pathway secretory pathway constitutive secretion constitutive secretion transported towards the cell membrane regulated secretion secretory pathway secretory pathway secretory pathway secretory pathway Secretory pathway secretory pathway secretory pathway regulated secretion secretory pathway secretory pathway regulated secretion constitutive secretion secretory pathway regulated secretion secretory pathway secretory pathway secretory pathway constitutive secretion transported towards the cell membrane transported towards the cell membrane secretory pathway secretory pathway secretion secretory pathway transported towards the cell membrane