Before revision: Based on data on gene expression profiles from microarrays for E. Coli and tumor tissues, I show the existence of heavy tails in the gene expression distribution functions, related to a set of strongly over- and under-expressed genes .
After revision: Based on data on gene expression profiles from microarrays for E. Coli and tumor tissues, I show the existence of heavy tails in the gene expression distribution functions, related to a set of strongly over- and under-expressed genes , as compared to the initial expression profile. This fact is manifested as heavy tails in the gene expression distribution functions.