Prolonged clotting time in Ip6k1^−/− mice. Change in turbidity as a function of time monitored spectrophotometrically at 405 nm in recalcified platelet releasates (PR) mixed with PPP. (A) Representative turbidimetry curves are shown for WT and Ip6k1^−/− samples. (B) Lag time, the time after recalcification at which an exponential increase in absorbance is observed, (C) clotting time, the time taken to reach the end of the exponential phase, (D) and the absolute change in absorbance between clotting time and lag time were measured in WT and Ip6k1^−/− samples of PPP+PR or PPP alone. Data, mean ± standard error (n = 6), were analyzed by a 2-tailed Student t test (*P ≤ .05; n.s., not significant, P > .05).