Schematic diagram of the human AR gene. The relative positions of the two transcription initiation sites (TIS I and II) and functionally known motifs; CpG islands, cAMP responsive element (CRE), helix-loop-helix-like (HL) motifs, a palindromic homopurine repeat (grey box) and GC-box (black box) which contains an SP1 binding site, are indicated (GenBank Accession No. NG009014.1). A grey circle denotes the T105A alteration identified in two primary breast tumours in the present study. DNA methylation was assessed in Regions 1-4, as denoted by black lines. UTR, untranslated region. ATG, translation start site.