Throughout his career, Jean Gruenberg and his colleagues identified several molecular factors directing endosomal biogenesis and dynamics, including various cytoskeleton-associated proteins, the small GTPases Rab5 and Rab7, Annexin A2 (previously named Annexin II), the vacuolar ATPase, COP coat proteins, the N-ethylmaleimide sensitive factor, the small transmembrane proteins of the p24 family, the p38 MAP kinase, phosphatidylinositol-3-phosphate, intra-endosomal cholesterol, the redox sensor thioredoxin-like protein, sorting nexins, the adaptor protein complex AP1, components of ESCRTs and associated proteins and the atypical phospholipid LBPA/BMP (see next section).