Updated publication reference for PubMed record(s): 35019937. Peroxisomes (POs) and the endoplasmic reticulum (ER) cooperate in cellular lipid metabolism and form membrane contacts, which are mediated by the peroxisomal membrane proteins acyl-coenzyme A-binding domain protein 4 and 5 (ACBD4/5) which bind to the resident ER protein vesicle-associated membrane protein-associated protein B (VAPB). ACBD4/5 bind to the major sperm protein (MSP) domain of VAPB via their FFAT-like [two phenylalanines (FF) in an acidic tract] motif. The molecular mechanisms which regulate membrane contact site formation and dynamics are not well explored, in particular in mammalian cells. Here, we reveal that peroxisome-ER associations via the ACBD5-VAPB tether are regulated by phosphorylation.