PAX1 and FOXF1 protein were expressed in all regions of the IVD and were significantly higher in the AF (PAX: P=0.0001; FOXF1: P=0.003) and NP (PAX: P=0.0001; FOXF1: P=0.0001) in comparison to the CEP and also significantly higher in the NP (PAX: P=0.0001; FOXF1: P= 0.0001) compared to the AF (Figures 3 & 4). Here, FOXF1 is linked to atrial fibrillation.