Various mutants of hFAF1-UBA binds to polyubiquitin chain in a different way in vivo HEK293T cells transfected with various mutant Flag-hFAF1s; (A) Flag-hFAF1 wild type, Glu21Ala, Thr28Asn, Val38Asn, and Ile41Asn. (B) Flag-hFAF1 wild type, ΔThr18 and Ile41Asn, were immunoprecipitated with antiFlag antibody and binding polyubiqutinated proteins were detected with antiubiquitin antibody.