Chemical Probe Discovery for DEAD-Box RNA-Binding Protein DDX21 Using Small-Molecule Microarrays

, suppressed P-TEFb-dependent phosphorylation of the RNA polymerase II CTD, and induced developmental defects in zebrafish embryos. These findings reveal a previously unexploited therapeutic avenue and establish KI-DX-014 as a chemical probe for dissecting the biological functions of DDX21 in both normal physiology and disease states.