MFAP1 KD specifically increases nuclear speckle size. (A) Western blots showing RNAi depletion of the indicated proteins (SRRM2, ZNF207, or PRPF38A) in U2OS cells. (B and C) Western blot showing the depletion of MFAP1 in Tig3 (B) or CHO (C) cells. Tubulin was detected as loading control. (D) Representative anti-SON immunofluorescence images of U2OS cells following siRNA treatment as indicated. (E) Representative anti-SON and anti-SC35 coimmunostaining of U2OS cells transfected with control siRNA (siCTRL) or siRNA against SRRM2 (siSRRM2). (F and G) Anti-SON immunofluorescence images of Tig3 cells (F) or CHO cells (G) after transfection with control siRNA (siCTRL) or siRNA against MFAP1 (siMFAP1). DNA (blue) was stained with DAPI. Scale bars: 10 µm.