Rhombotin-1 is a protein that in humans is encoded by the LMO1 gene. This locus encodes a transcriptional regulator that contains two cysteine-rich LIM domains but lacks a DNA-binding domain. LIM domains may play a role in protein interactions; thus the encoded protein may regulate transcription by competitively binding to specific DNA-binding transcription factors. Alterations at this locus have been associated with acute lymphoblastic T-cell leukemia. Chromosomal rearrangements have been observed between this locus and at least two loci, the delta subunit of the T-cell antigen receptor gene and the LIM domain binding 1 gene. Alternatively spliced transcript variants have been described.