As demonstrated by other studies [33] , HB-EGF mRNA was also upregulated in activated human CD4 T cells (Figure 2A) , although the levels were lower than AR and peaked at a later time ( Figure 2B ). TGFa and EREG mRNA were also detected in resting CD4 T cells, but not increased during TCR activation. Other EGF members were undetectable. In our previous mouse experiments [27] , AR and HB-EGF were also the only EGF family members induced by TCR stimulation (data not shown). Expression of HB-EGF protein was confirmed by cell surface and intracellular staining (data not shown).