NTRK2 and atrial fibrillation: However, IVDs that received NTG-101, four weeks post-injury, showed a significantly lower number of positive cells showing immunostaining for NGFr/TrkA (p = 0.0001), BDNF (p = 0.009), TrkB (p = 0.002) and CALCRL (p = 0.008) as compared to PBS injected IVD-AF tissue sections (Figure 6).