A screen for mitotic PP2A-B56 substrates identifies Cdc20. (A) A schematic of the approach used to identify PP2A-B56 substrates in nocodazole arrested cells. (B) Summary of the screen results categorizing sites based on the presence of validated or predicted LxxIxE motifs. (C) Log2 ratio of regulated phosphorylation sites versus P value. Sites in proteins with validated LxxIxE motifs are indicated with protein names as well as Cdc20 T70. (D and E) Examples of identified sites in the screen and whether they contain validated, predicted, or no LxxIxE motifs. The protein name is indicated followed by the specific phosphorylation site detected and found to be regulated. The log2 ratio of B56 inhibited sample (LxxIxE peptide) vs. control-treated sample (AxxAxE) is indicated followed by the P value, calculated using a two-tailed Student’s t test assuming unequal variance. LC/MS, liquid chromatography-mass spectrometry.