RBM39 is an RNA-binding protein involved in transcriptional co-regulation and alternative RNA splicing. Recent studies have revealed that RBM39 is the unexpected target of aryl sulphonamides--Indisulam, E7820, and CQS (Table ), which act as molecular glues between RBM39 and the DCAF15-associated E3 ubiquitin ligase complex leading to selective degradation of RBM39. Loss of RBM39 leads to aberrant splicing events and differential gene expression, thereby inhibiting cell cycle progression and causing tumor regression in a number of preclinical models. Indisulam, E7820, and CQS, have been evaluated in clinical trials as antitumor drug candidates. Table .