Protein display in 2D gels of Y. pestis KIM6+ membrane fractions in the pI range 4-7 (-Fe vs. +Fe conditions). Proteins were derived from cell growth in the presence of 10 μM FeCl3 at 26°C (top) or absence of FeCl3 at 26°C (bottom). Gels (20 × 25 cm) were stained with CBB, with five gel replicates representing each of the groups, and subjected to differential display analysis using the software Proteomweaver v.4.0. Protein assignments to a spot (or a spot train) required validation by MS data from at least two representative gels. The denoted spots and spot trains are equivalent to those listed in Table 2 with their '-Fe vs. +Fe' protein abundance ratios and other data.