MYC and plasma cell myeloma: For example, the substantial c-MYC downregulation observed upon treatment with DC-34 in multiple myeloma cells40 is consistent with the high levels of P1-driven c-MYC expression characteristic of these cancers86,87, whereas it is ineffective in other cells that are less reliant on the P1 promoter for c-MYC expression (i.e., MCF7).