RAC1 and thymoma: The WNT4-driven expression of JNK in a stable AB thymoma cell line has been reported previously (41, 44) and conforms to our finding that the WNT4 autocrine loop depends on WNT4-driven RAC1 and JNK expression, i.e., activation of the non-canonical WNT/PCP pathway (52) in neoplastic pTECs derived mainly from aggressive TETs (Supplementary Figure 5).