Updated project metadata. We found that LC3B is phosphorylated in vitro by STK3, STK4, NEK9, and PKCζ. To identify phosphorylation sites following in vitro phosphorylation, GST-LC3B was overexpressed in E. coli, purified using glutathione-Sepharose 4 Fast Flow beads and incubated in kinase assays with recombinant kinases or FLAG-tagged kinases immunopurified from transiently transfected HEK293 cells