PDCD1 and lymphoma: Consistent with the development of an AITL condition, the transcriptome of the lymphoma samples obtained from Trp53ER/ER;Vav1ΔC/ΔC mice includes the upregulation of AITL‐specific genes such as Bcl6, Maf, Il21, Pdcd1, and Icos [46] (Fig. 3D).