POMC and neoplasm: Since so much is known about PAM trafficking in pituitary cells [21, 27], each GFP-tagged targeted PAM protein was transiently expressed in AtT-20 corticotrope tumor cells, where its localization could be compared to that of PAM/GFP and established markers for cis-Golgi (GM130), TGN (TGN38), secretory granules (ACTH) and lysosomes (LAMP1).