Controls osteoclast survival and size (By similarity). As a dimer with JUN, activates LIF transcription (By similarity). Activates CEBPB transcription in PGE2-activated osteoblasts (By similarity). Heterodimer (By similarity). Interacts with the BAF multiprotein chromatin-remodeling complex subunits SMARCB1 and SMARCD1 (By similarity). Interacts with ARID1A and JUN (By similarity). Belongs to the bZIP family. Fos subfamily.