We found no genes with YopM-associated significant changes in expression at 18 h p.i. There was, however, a YopM-associated downregulation of the gene for Egr1, at 1 h p.i. This is the earliest time examined so far for Y. pestis infection in-vivo and was possible because of the synchronous infection used in this work. The gene discussed is EGR1; the disease is infection.