The rate of kallikrein cleavage of E coli–expressed HK recombinants as observed using SDS-PAGE. Quantitative densitometric analysis of the stained protein bands on standard reduced SDS-PAGE was performed on the recombinant GST–HK4-6 from 3 rat strains when cleaved by kallikrein as described in “Materials and methods.” ○ indicates Lewis; □, Fischer; and ▿, Buffalo. Mean ± SEM, n = 3. The disappearance of a 62-kDa band was followed to quantify the cleavage rate. No difference in the cleavage rates were observed.