Key pioneer transcription factor of B-cell specification and commitment (PubMed:27807034). Recognizes variations of the palindromic sequence 5'-ATTCCCNNGGGAATT-3'. Operates in a transcription factor network to activate B-cell-specific genes and repress genes associated with alternative cell fates. For instance, positively regulates many B- cell specific genes including BCR or CD40 while repressing genes that direct cells into alternative lineages, including GATA3 and TCF7 for the T-cell lineage. In addition to its role during lymphopoiesis, controls the thermogenic gene program in adipocytes during development and in response to environmental cold (By similarity). . (Microbial infection) Acts as a chromatin anchor for Epstein- Barr virus EBNA2 to mediate the assembly of EBNA2 chromatin complexes in B-cells (PubMed:28968461). In addition, binds to the viral LMP1 proximal promoter and promotes its expression during latency (PubMed:26819314). {ECO:0000269|PubMed:26819314, ECO:0000269|PubMed:28968461}. This is the function of EBF1 (EBF transcription factor 1, Ensembl gene identifier ENSG00000164330).