Fig 1: The nucleolar concentric organization. (A) The nucleolus is a membrane-less organelle composed of three distinct sub-compartments: the granular component, the dense fibrillar component and the fibrillar centre. The function in ribosomal RNA processing stages and protein markers of each substructure is indicated. (B) Granular component and dense fibrillar component were labelled using endogenous NPM1 and fibrillarin antibodies respectively. Nuclei were stained using DAPI. Enlarged areas are indicated by the white box. Granular Component's edges (i.e. the edges of the nucleolus) are outlined by a dotted line. Dense fibrillar components are indicated by the white arrow. Scale bars: 10 µm, except the enlarged region of interest (upper right corner of the bottom-right panel): 2.5 µm. Representative images of the same labeling in UbKEKS-knockout cells are available in Fig. S4 (n=1, for illustrative purpose).