We used Lamp1 to identify lysosomes that might have a secretory function, as Lamp1 is found on non-degradative lysosomes, and these lysosomes are often found at the plasma membrane.46,47 In diabetes-mimicking αTC1-6 cells, Lamp1+ lysosomes appear to be distributed at the plasma membrane, together with glucagon+ secretory granules. The gene discussed is GCG; the disease is diabetes mellitus.