Since there were no significant changes in Sox9 mRNA levels, and no increase in those of Pax9, in the control vs. the Pax1-silenced AF pellets under chondrogenic conditions, reduced Pax1 expression could ultimately lead to augmented transcriptional activity of SOX trio (SOX5, 6, 9) complexes, which drive robust Acan expression. This evidence concerns the gene SOX9 and atrial fibrillation.