For example, SMARCA4 deficiency was the most common driver in small cell carcinoma of the ovary hypercalcemic type (SCCOHT) [22] and thoracic SMARCA4-deficient undifferentiated tumor (SMARCA4-DUT) [23], while the role of SMARCA2 in the development and progression of undifferentiated carcinomas has been neglected, and more studies are needed in the future. Here, SMARCA4 is linked to undifferentiated carcinoma.