BCL9 and cancer: In human cancers, there are increasing evidence that intratumoral cDC1 are associated with the improved prognosis and responses to cancer immunotherapy.6,9 Having established that targeting BCL9/BCL9L facilitates activation and antigen presentation of cDC1, we guessed that targeting BCL9/BCL9L may promote cDC1 accumulation in tumors owing to the increased numbers of intratumoral cDC1 from B16-OVA tumor-bearing Bcl9/Bcl9l deficiency mice shown by single-cell analysis (Fig. 4g).