DBC1 is a component of a SNB substructure and a novel RNase-sensitive NB. (A) The SNB is separated into two distinct substructures upon HNRNPL depletion. Immunofluorescence analysis of Sam68 and DBC1 in control and HNRNPL-depleted (siHNRNPL) cells is shown on the left. Quantification of fluorescence by the line scan marked in the merge panel (marked as 1 and 2) is shown on the right. The green and pink lines correspond to the signals of Sam68 and DBC1, respectively. The cell populations (%) in which Sam68 and DBC1 signals overlap are shown in the merge panels (>100 cells, n = 3). (B) DBC1 foci are detectable under the cold shock conditions shown on the left. Immunofluorescence analysis was performed as in A. (C) Distinct DBC1 foci (DBC1 bodies) are detectable in other cell lines. Immunofluorescence analysis was performed to detect Sam68 and DBC1 in five human cell lines (HeLa, SW-13, T24, MCF-7, and HCT116) and a mouse cell line (NIH3T3). In the merge panels, the cell populations (%) in which Sam68 and DBC1 signals overlap are shown by white numbers, and those with nonoverlapping Sam68 and DBC1 signals are shown by magenta and green numbers, respectively (>100 cells, n = 3). (D) No other SNB components localize to the DBC1 body in HCT116 cells. Immunofluorescence analysis of HNRNPL and HNRNPD with DBC1 was performed in HCT116 cells. (E) The DBC1 body does not overlap with other known NBs in HCT116 cells. Immunofluorescence analysis of various NB markers with DBC1 was performed in HCT116 cells. Bars, 10 µm.