BMAL2 and neoplasm: Interestingly, Ha et al. established that alteration of Arntl2 solely impacts cells of the tumor, with no impact on supporting stromal cells [7]; when hybrid Arntl2 knockout mice were compared with wildtype Arntl2 mice after orthotopic injection of syngeneic 4T1 mammary cells, there were no differences in the number of lung metastases, suggesting that Arntl2 acts in a tumor cell–autonomous manner.