miR-15a/16 expression in normal human lymphoid tissues and MM cells. (A) miR-15a or miR-16 colocalization with PC marker CD138 in human LNs. CD138 expression was assessed by IF (green), followed by ISH analysis for miR abundance (red) on the same frozen slide. 4′,6-Diamidino-2-phenylindole (DAPI; blue) was used for nuclear counterstaining. One representative example is shown. Note colocalization of miR-15a, miR-16 signal, and CD138 in PC-rich regions as well as in individual PCs (insets, arrowheads). Scale bar, 800 µm. (B) miR-15a or miR-16 (ISH, purple) and CD138 (IHC, brown; counterstain, blue) expression in consecutive FFPE LN sections from a healthy individual. Note higher miR-15a and miR-16 abundance in a PC cluster (inset) and germinal center (GC) compared with other lymphoid cells. Scale bar, 200 µm.