DUSP14 is involved in the inactivation of MAP kinases. This proein dephosphorylates ERK, JNK and p38 MAP-kinases. In addition to antigen recognition by the T-cell receptor, T-cell activation requires a second signal from a costimulatory receptor, such as CD28, which interacts with B7-1 (CD80) and B7-2 (CD86) ligands on antigen-presenting cells. CD28 costimulation induces transcription of interleukin-2 and stabilizes newly synthesized IL2 through the activation of mitogen-activated protein kinases (MAPKs), such as ERK and JNK, and the subsequent creation of AP1 transcription factor. DUSP14 is a negative regulator of CD28 signaling.