FOS and angioimmunoblastic T-cell lymphoma: Activating mutations involved in the AP-1/MAPK pathway were detected in a fraction of AITL cases: three missense mutations of KRAS (G13D, A18D, and I36M) and two missense mutations of STAT3 (E616G and E616K), all of which result in constitutive activation of the AP-1 transcription factor c-FOS [140].