ATF6 and plasma cell myeloma: <b>Methods:</b> Multiple myeloma (MM) cell lines (H929 and U266) and their carfilzomib-adapted derivatives were used to establish and validate droplet digital PCR (ddPCR) assays targeting ER stress (<i>uXBP1, ATF6</i>) and autophagy-related (<i>LAMP2A</i>) transcripts.