Multivariate analysis of proteomic data.

<p>(A) PCA plot of the expression profiles from K562 cells untreated (circles) and after 24-h exposure to <b>IND_S1</b> (triangles), <b>MEL_T1</b> (squares), <b>IND_S7</b> (diamonds), <b>MEL_S3</b> (crosses). Log-transformed data were used. Each symbol represents a 2-DE gel from each treatment group. First and fourth ordination axes are plotted explaining 80 and 5% of the overall variance in the dataset, respectively. (B) Visualization of the SOM component planes of proteome data for all treatment series. Ratios between expression levels in K562 cells treated with the four synthetic small molecules and control cells were calculated and log₂-transformed. Each presentation illustrates the weights that connect each input to each of the artificial neurons, resulting in a sample-specific proteome-wide map (darker colors represent larger weights). All figures are linked by position: in each display, the hexagon in a certain position corresponds to the same map unit.