CD19 and Miyoshi myopathy: In CXCR4+ MM, relative plasma cell surface CXCR4 expression levels were significantly higher than those on intraindividual CD19+ B cells, CD3+ T cells, CD34+ HSPCs, and CD14+ monocytes (Fig1B–D; gating strategy depicted in Supplementary Fig S1; representative data shown in Supplementary Fig S2A–D), indicating that a CXCR4-directed PET tracer could be suitable for MM imaging.