(A) The etiology of HTLV-1 infection (splicing and scale are ignored in the simplified virus genome) and conversion to ATL. (B) ATL etiology involves promoter CpG hypermethylation that silences downregulators of TCR signaling, including Themis, the Titaness personification of natural law. Expansion of chronic ATL xenografts in mice was significantly inhibited by HMA therapy with OR-21.