Furthermore, other β cell-specific transcription factors, such as Nkx2.2, Nkx6.2, and Pax4 that are detected in normal β-cell development, were neither induced nor increased by PDA-gene transfer, suggesting that transient β-like cell induction does not occur in the similar molecular cascade to that of the regular developmental process of β cells. This evidence concerns the gene PAX4 and Patent ductus arteriosus.