PFI-6 is a selective and non-cytotoxic probe targeting the YEATS domain of MLLT1 (ENL YEATS1) and MLLT3 (AF9 YEATS3), with IC50 values of 140 nM for MLLT1 and 160 nM for MLLT3. It serves as a molecular tool to investigate the role of MLLT1 3 in diseases and genome validation studies [1].