To investigate the selectivity requirements of BET inhibitors as enhancers of PGRN, we employed iBET-BD1 (BD1-selective, KD = 31 nM and 5.6 μM against recombinant BRD4 BD1 and BD2, respectively), ABBV-744 (BD2-selective, KD = 435 nM and ≤ 2.0 nM against recombinant BRD4 BD1 and BD2, respectively), and mivebresib (pan-BD, KD ≤ 2.8 nM and ≤ 2.0 nM against recombinant BRD4 BD1 and BD2, respectively) (Fig. 5A)63,64,68. Here, BRD4 is linked to Behcet disease.