Additional recurrent mutations in SF3B1 occurred at codon 666 (K666Q and K666E) in 9% of mutant tumours (2/23), and non-recurrent mutations included G241*, N626D, A633V, Y765C, and D781E, which were found in 22%...Here we demonstrate that treatment of SF3B1 mutant and wild-type cell lines with spliceostatin A resulted in selective inhibition of the growth of mutant cells and in the disruption of the conserved splicing signature.