– Human Histone Chaperone ASF1A (ASF1A) belongs to the H3/H4 family of histone chaperone proteins. ASF1A is ubiquitously expressed in many cells and tissues, interacting with histones H3 and H4. ASF1A cooperates with Chromatin Assembly Factor 1 to promote replication-dependent chromatin assembly and with HIRA to promote replication-independent chromatin assembly. In addition, ASF1A is necessary for the formation of senescence-associated heterochromatin foci (SAHF) and efficient senescence-associated cell cycle exit.