Deletion of PDCD2L causes the accumulation of free 60S ribosomal subunits. (A) Sucrose gradient analysis of total extracts prepared from WT and PDCD2L-null HeLa cells (clones 1A3 and 3B2). The positions of free small (40S) and large (60S) ribosomal subunits, monosomes (80S), and polysomes are indicated. (B) Quantification of ratios of 60S/40S free ribosomal subunits expressed relative to values for wild-type HeLa cells. Data and error bars represent the means and standard deviations, respectively, from 7 independent (1A3) and 6 independent (3B2) experiments. ****, P value of <0.0001, as determined by Student's t test. (C) Sucrose gradient analysis of total extracts prepared from WT (1) and PDCD2L-deleted (clone 1A3) (2 and 3) HeLa cells that were previously transfected with an empty vector (EV) control (1 and 2) or a DNA construct expressing Flag-PDCD2L (3). (D) Western blot analysis showing the expression of Flag-PDCD2L in PDCD2L-null cells (lane 3). The band comigrating with endogenous PDCD2L in lane 3 is a degradation product generated from Flag-PDCD2L.