Immunogen sequence: TAPPTLALHY HPHPFLNSVY IGPAGPFSIF PSSRLKRRPS HCELDLAEGH QPQKVA Antigen sequence identity: Mouse 91%; Rat 93%. Lyl-1, TAL1 and TAL2 are part of a family of basic helix-loop-helix (bHLH) proteins implicated in T cell acute leukemia. TAL1