SMARCA1 and cancer: Somatic mutations in SWI/SNF subunit genes occur in over 20% of all human cancers,[1] with ARID1A being the most frequently mutated subunit across all cancer types.[2] Notably, deleterious ARID1A mutations are frequently observed in morphologically normal tissues and non‐malignant cells of older individuals.[3, 4, 5, 6, 7] This raises a critical question: can the loss of a single tumor suppressor gene like ARID1A alone transform healthy cells into cancer cells?