To further investigate the upstream target that drives the increased pSTAT3 (Y705) levels observed in SMARCB1 KO BLCA cells, we treated spheroids with Itacitinib, a specific JAK1 inhibitor24,25, that abrogated pSTAT3 (Y705) levels in SMARCB1 KO derived spheroids (Fig. 3G). Here, JAK1 is linked to bladder transitional cell carcinoma.