To confirm the biochemical isoform selectivity of IOA-244, idelalisib and umbralisib, the compounds were tested for growth inhibition of cancer cell lines especially sensitive to inhibition of specific PI3K class 1 isoforms: T-47D for PI3Kα, LNCAP for PI3Kβ, THP-1 for PI3Kγ, and SU-DHL-6 for PI3Kδ (Table 2; refs. 30–33). Here, PIK3CD is linked to cancer.