Here the rapid acquisition of plakophilin-2 to the non-desmosomal plaques of these tumor cell AJs, in particular the fact that it appears in the earliest in vitro culture passages of cardiac valvular interstitial cells from various mammalian species [23], suggests that the addition of plakophilin-2 alone—or together with plakophilin-3—to these junctions is somehow related to the induction of proliferation and cell cycle growth. Here, PKP2 is linked to neoplasm.