The cellular levels of SigX during competence induction by XIP in CDM and the effects of mecA , clpC or clpP deletion on the stability of SigX and competence. A. Western blot analysis of the cellular levels of SigX in strain XT-His1 (wt) by the anti-His antibody. The protein loading controls this strain were detected by Western blotting using the anti-S. mutans antibody. B. The effects of mecA, clpC or clpP deletion on the transformation efficiency of S. mutans strains UA159 (wt), XT-D1 (∆comX), XT-D4 (∆mecA), XT-D7 (∆clpC) and XT-D8 (∆clpP). C. Western blot analysis of the effects of mecA, clpC or clpP deletion on the cellular levels of SigX in strains XT-His1 (wt), XT-His2 (∆mecA), XT-His3 (∆clpC) and GF-His1 (∆clpP) using the anti-His antibody. D. The protein bands representing the cellular levels of SigX in these strains were scanned and the intensities of the bands were converted as the relative integrated density values (RIDV), which were normalized to a maximum value of 1.0 for each strain.