CD38 and plasmacytoma: The plasmacytoma‐bearing mice received various treatments: i.v EVs‐Dox and CD38‐EVs‐Dox (EVs‐Doxi.v and CD38‐EVs‐Doxi.v), MN‐delivered EVs‐Dox and CD38‐EVs‐Dox (EVs‐DoxMNs and CD38‐EVs‐DoxMNs), with PBS as the negative control (Figure S9).