FACT is heterodimer protein complex and histone chaperone that plays an important role in maintaining and modifying the chromatin structure during various DNA-dependent processes. FACT is involved in nucleosome assembly de novo and in the preservation and recovery of the nucleosome structure during and after transcription, replication and DNA repair. During transcript elongation, FACT reduces the height of the nucleosome barrier and supports the maintenance of nucleosomes during and after the passage of RNA polymerase II. In this process, FACT interacts with histone H2A-H2B dimer within nucleosomes, thus, facilitating uncoiling of nucleosomal DNA from the octamer of histones. It also facilitates the subsequent recovery of the canonical nucleosome structure after transcription. FACT also plays an important role in the transformation of human cells and in maintaining the viability of tumor cells.