Cytotoxicity of the SCIN and CHIPS proteins. (a) LDS-PAGE analysis of the purified S. aureus SCIN and CHIPS proteins, and the LysM domain of the S. aureus Sle1 protein. (b) To assay the cytotoxicity of SCIN, CHIPS and LysM domain, HeLa cells were incubated with different amounts of the purified proteins for 24 h. Subsequently, the viability of the HeLa cells was assayed by measuring the reduction of MTT. The statistical significance of the observed differences in the killing of HeLa cells was assessed using one-way ANOVA and a subsequent Dunnett correction to adjust the P-values (SCIN 5 μg/ml vs. LysM 5 μg/ml, P < 0.0001; CHIPS 5 μg/ml vs. LysM 5 μg/ml, P < 0.0001; SCIN 2 μg/ml vs. LysM 2 μg/ml, P = 0.0053; CHIPS 2 μg/ml vs. LysM 2 μg/ml, P = 0.0003; SCIN 1 μg/ml vs. LysM 1 μg/ml, P = 0.0102; CHIPS 1 μg/ml vs. LysM 1 μg/ml, P = 0.0006). *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001; P < 0.05 was considered significant.