The protein encoded by this gene is a multifunctional, nuclear phosphoprotein that plays a role in cell cycle progression, apoptosis and cellular transformation. It functions as a transcription factor that regulates transcription of specific target genes. Mutations, overexpression, rearrangement and translocation of this gene have been associated with a variety of hematopoietic tumors, leukemias and lymphomas, including Burkitt lymphoma, in human. There is evidence to show that alternative translation initiations from an upstream, in-frame non-AUG (CUG) and a downstream AUG start site result in the production of two isoforms with distinct N-termini, in human and mouse. Under conditions of stress, such as high cell densities and methionine deprivation, there is a specific and dramatic increase in the synthesis of the non-AUG initiated protein, suggesting its importance in times of adversity. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Apr 2010]