TCR and cAMP signals synergize to induce AR expression. TCR activation alone (which transiently elevates cAMP [41] ) induced transient AR mRNA expression (Figure 7A) , and a strong cAMP agonist (PKA activator 8-CPT-cAMP) also induced low levels of AR in the absence of other signals. However, TCR and PKA signaling synergized to induce higher and more sustained levels of AR and HB-EGF mRNA ( Figure 7A ), as well as high levels of AR protein (supernatant plus cell-associated, Figure 7B ). This strong synergy contrasts with a previous study [40] , possibly due to the presence of basophils in the responding population in that study.