High-mobility group protein HMG-I/HMG-Y is a protein that in humans is encoded by the HMGA1 gene. This gene encodes a non-histone chromatin protein involved in many cellular processes, including regulation of inducible gene transcription, DNA replication, heterochromatin organization, integration of retroviruses into chromosomes, and the metastatic progression of cancer cells. HMGA1 proteins are quite small (~10-12 kDa) and basic molecules, and consist of three AT-hooks with the RGRP (Arg-Gly-Arg-Pro) core motif, a novel cross-linking domain located between the second and third AT-hook, and a C-terminal acidic tail characteristic for the HMG family comprising HMGA, HMGB and HMGN proteins.