When stably transfected into human osteosarcoma U2OS cells, the streptavidin–CD74 construct (the “ER hook”) and the streptavidin–golgin84 construct (the “Golgi hook”) were correctly expressed in their target organelles, as demonstrated by co-staining with the endogenous ER protein calreticulin (CALR) or the endogenous Golgi protein B4GALT1 (Fig. 1b, c). Here, CALR is linked to osteosarcoma.