ARID1A and in situ carcinoma: Importantly, while median ARID1A protein expression was increased in all tumor subgroups compared to NU controls, the percentage of cases showing ARID1A protein loss (Remmele score: 0–2) positively correlated with increasing stage and grade (NU = 0, pTa LG = 1.6, pTa HG = 3.3, CIS = 9.1, pT1 HG = 12.9, MIBC = 14.1%) (Fig 3H).