CK2 activity is reduced by CK2 inhibition in X. laevis extract. (A) CK2 activity of six extracts (three meiotic and three mitotic) used in proteomics and phosphoproteomics experiments in control and CK2i treated samples for each dataset. Statistical significance was determined by paired two-tailed t tests (** = P < 0.005, *** = P < 0.0005). Data distribution was assumed to be normal, but this was not formally tested. (B) Results of CK2 activity assay of samples containing 0–1 mU/reaction of purified CK2 alpha/beta protein (MBL) three times on different days (assays 1, 2, and 3). Linear regression analysis was used to fit a trendline to absorbance data from each assay. The slopes of the trendlines of the three assays were not significantly different (P = 0.7962). (C) CK2 activity of 500 µg/ml meiotic Xenopus egg extracts treated with 50 μM CK2i (n = 16 extracts), 25 μM CK2i (n = 13 extracts), or 1 μM Plk1i (n = 9 extracts) normalized to DMSO control. Statistical significance was determined by one sample two-tailed t test against hypothetical mean of 1 (** = P < 0.005). Data distribution was assumed to be normal, but this was not formally tested. (D) Images of immunofluorescence of representative fields of metaphasic CSF X. laevis egg extract spindle assembly reactions in the presence of 25 μM CK2i or DMSO as indicated. Maximum intensity projections are shown. Tubulin (magenta), DNA (cyan). (E) Images of immunofluorescence of representative fields of metaphasic CSF X. laevis egg extract spindle assembly reactions in the presence of 1 μM Plk1i or DMSO as indicated. Maximum intensity projections are shown. Tubulin (magenta), DNA (cyan).