Pearson correlation between the vectors of fold change values (all probe sets, treated v.s. untreated conditions) for the four cell lines

Notice that the responses of both the PDGFRβ knock out cell line and PDGFRα null cell line to PDGF-BB treatment are more similar to that of the WT cell line than any of the others. The response of the double null cell line is essentially uncorrelated with the response of the other three cell lines.