PSMA3 and AL amyloidosis: Mechanistically, MSC-derived exosomes conferred bortezomib resistance by transferring PSMA3 and lnc PSMA3-AS1 to multiple myeloma cells, and lnc PSMA3-AS1 impaired the sensitivity of multiple myeloma cells to bortezomib by upregulating PSMA3 expression by forming an RNA duplex with PSMA3-AS1 pre-mRNA in vitro.