Proteolytic processing of ADAMTS6 and PAPPA1. A) Aliquots of CD4+ T cell lysates from wild-type and FURIN knock-out mice were run on SDS-PAGE and ADAMTS6 and ACTIN were detected by Western blot. B and C) 293e cells were transfected with FURIN-myc-his or PCSK7-flag together with wild-type, PCSK cleavage site mutated flag-PAPPA1-myc (mut) or PCSK7-favored leucines harboring flag-PAPPA1-myc (R3L) constructs, and detected anti-flag or anti-Myc antibodies as indicated. Unprocessed PAPPA1 is indicated with an asterisk and processed with an arrow. All experiments were repeated at least twice with similar results.