Fig. 4. SANB composition varies with the advancement of senescence. (A) Progression of senescence [dividing cells (A) to late senescent cells (E)] is associated with a decrease in the nucleolar component, fibrillarin, but an increase in poly-ubiquitin conjugates. Fibrillarin is red, ubiquitin appears green and PML blue. (B) Bar graph representing the percentage of WI-38 cells with SANB depending on the state (dividing/senescent) of the cells. The columns represent the average of three independent experiments.