Four major contributors proposed as the source of autophagic membrane: 1) ER, endoplasmic reticulum; 2) G/SP, Golgi/secretory pathway; 3) PM, plasma membrane; 4) MT, mitochondria. 5) Autophagic pathway has been stylized into a logo flow chart (crescent, initiation/phagophore formation; double membrane, early/nondegradative autophagosome; single membrane with dense content, degradative autolysosome). SLRs, sequestosome 1/p6-lke receptors. PI3P, phosphatidylinositol 3-phosphate.