NFATC1 and thymoma: Instead of being induced as the endogenous Nfatc1 gene by the phorbol ester TPA and the Ca++-ionophore ionomycin (which mimic immune receptor signals), inducers of protein kinase A, such as forskolin, led in combination with ionomycin to the strongest induction of P1 in EL-4 thymoma cells (9).