ACAN and atrial fibrillation: Compared with the respective mean concentration levels (594 ± 11 ng/μg and 35.1 ± 1.4 ng/μg) in NP and AF tissues of wild-type rabbits, the levels of aggrecan in NP and AF tissues of APOE-knockout rabbits were reduced by 28.9% and 26.4% respectively (p < 0.0001) (Table 2, Fig 5A).