Fig 2: CKS2, CDK1, and SSBP1 protein–protein complexes in HeLa cells. Immunofluorescence images (maximal projection of z-stacks) of (A) CKS2-CDK1;, (B) CKS2-SSBP1;, and (C) CDK1-SSBP1 PLA foci in interphase cells. The PLA foci are shown in red and DNA in blue. In panel A, foci are present in the nucleus and cytoplasm. In panels B and C, foci are present in the cytoplasm only, including a few lying above the nucleus. (D) Frequency distribution showing number of PLA foci per cell for the foci types in panels A-C. A total of 100 randomly selected interphase cells in an exponentially growing cell culture were counted. For CKS2-CDK1, data for nuclear and cytoplasmic foci are shown separately.

Fig 3: Modulation of Wnt signalling in MLL-translocation cell lines by CKS1 and CKS2. TCF/LEF activity was measured in (A) KOPN-8 (MLL-ENL) and (B) THP-1 (MLL-AF9) cell lines using the TOPFlash reporter plasmid (or FOPFlash plasmid control) and pRL-TK Renilla control. Cell lines were co-transfected with siRNA to knockdown expression of CKS1B, CKS2 or CKS1B + CKS2. Values are represented as fold change RLA versus Non-specific siRNA treated cells. Significance was tested using the Student's t-test (N = 3).

Fig 4: Tumor protein–protein complexes and survival analysis in patients. (A) Cytoplasmic and nuclear CKS2 expression (left), cytoplasmic SSBP1 expression (middle), and cytoplasmic and nuclear CDK1 expression (right) by immunohistochemistry in histological sections. (B) CKS2-SSBP1 PLA foci (brown dots) in two different tumors (left, middle) and CDK1-SSBP1 PLA foci (brown dots; right). Arrow points to PLA foci in left and right inset panels. (C) Kaplan-Meier curves of progression-free survival for patients with high (composite score >0) and low (composite score of zero) cytoplasmic CKS2 expression. (D) Kaplan-Meier curves of progression-free survival for patients with high (composite score >2) and low (composite score =2) nuclear CKS2 expression. (E) Kaplan-Meier curves of progression-free survival for patients with high and low cytoplasmic and/or nuclear CKS2 expression. (F) Box plot of tumor volume for 31 patients with low and 16 patients with high cytoplasmic and/or nuclear CKS2 expression. *, statistically significant difference (P < .05) between the patient groups. (C-E) P value from log-rank test and number of patients are indicated.

Fig 5: Characterization of the transcriptional program associated with CKS2 expression in patients. Cellular compartments (A) and hallmarks (B) enriched in the transcriptional program based on 150 cohort 1 patients, 135 cohort 2 patients, and 41 patients in the immunohistochemistry cohort. (A) Percentage of unique genes annotated to the cellular compartments is presented. The cellular component ontology terms included in each compartment are defined in Table S2A.