MED12 and cancer: Five non-synonymous mutations were located in genes described as tumor drivers in the COSMIC Cancer Gene Census (CGC) database [16], namely Pten, Pik3r1, Pik3ca, Med12, and Kras. In addition, we found two different Robo1 mutations in mouse C25 and two different Traf3 mutations in two different TCL1 mice (Fig. 2), one non-frameshift insertion of a leucine encoding triplet near the C-terminus of TRAF3 (mouse E31) and one affecting splicing of exons 5 and 6 (mouse D22; Supplement Table 4).