The C-terminal region of CgA is cleaved by thrombin in blood during fibrin clot formation. (A) Analytical recovery of recombinant CgA in serum and plasma samples obtained from murine blood (n = 3) spiked with 10nM CgA, as measured by the indicated ELISAs. The analytical recovery of FRs was obtained by calculating the difference between 436/439+FRs and 436/439-ELISA. (B) Detection of natural circulating CgA in plasma (P) and serum (S) samples obtained from the same human subjects (n = 6), as measured by the indicated assays (mean ± SD; **P < .01, ***P < .001; 2-tailed t test).