SMAD4 and lung adenocarcinoma: The non-canonical arm of TGFβ signal transduction in PDAC is known to involve RAC1 signaling, i.e., RAC1 was discussed as a potential mediator of TGFβ-stimulated invasion in PDAC organoids with mutant DPC4 [64], and in lung adenocarcinoma A549 cells a NSC 23766-induced decrease in RAC1 activity partially blocked TGFβ1-induced EMT and the increase in ALDHhigh CSCs [48].