Cleavage of PAR-1 N-terminal TR33-62 peptide at Arg41 by rwt APC and APC variants. HPLC was used to monitor TR33-62 cleavage by APC over time as disappearance of the TR33-62 peptide substrate peak (open symbols) and as appearance of the TR42-62 peptide product peak (solid symbols). ▪ and □ indicate rwt APC; • and ○, 229/230-APC; ♦ and ⋄, 3K3A-APC; and ×, S360A-APC. The pooled data points of 3 to 5 independent experiments are shown for rwt APC and the 2 antiapoptotic APC variants. No cleavage was observed for the S360A-APC that lacks the active site Ser (× denotes no changes in TR33-62 or TR42-62). Error bars indicate SEM.