Immunogen sequence: RRVQSQWAST RGGHKERPTV MLFPFRNLGS PTQVISKPES KEEHAIYTAD LAMGTRAAST GKSKSPCQTL GGRALKENPV DL. TRF1 is a negative regulator of telomere length maintenance. Recently two proteins, tankyrase and Tin2, which bind to mammalian TRF1, have bee