JUN and neoplasm: Tumor burden was significantly (P = 4.5 × 10–4) increased in the lungs of c-Junfl/fl; lsl-Jnkk2-Jnk1; lsl-K-RasG12D mice compared with c-Junfl/fl; lsl-K-RasG12D mice, suggesting that c-Jun loss and increased JNK activity cooperate to promote tumorigenesis (Figure 4B and Supplemental Figure 3F).