Expression of Snk/Plk2 is down-regulated in lymphomas. (A) Snk/Plk2 mRNA is down-regulated in DG75 BL cells relative to EBV-immortalized B LCLs. RT-PCR was performed to analyze expression of Snk/Plk2 in DG75 and pooled LCLs as indicated. RT-PCR to detect the mRNA of Snk/Plk2 and GAPDH was performed as described in “Materials and methods.” Mr indicates 100-bp molecular weight markers. (B-C) Expression of Plks in normal and neoplastic B lymphocytes. (B) RT-PCR analysis of Plks 1-4 in BL and LCLs and other B-cell lymphomas as shown. The identity of each cell line is shown above the gels. A loading control (GAPDH) is also shown. RNA was isolated from cell lines and expression of each Plk determined by RT-PCR as described in “Materials and methods.” (C) Western blot analysis of Plks 1-4 in BL, LCL, and other B-cell lymphoma cell lines as indicated. The identity of each cell line is shown above the blots. Expression of loading control gene (PCNA) is also shown. Antibodies against Snk/Plk2 recognize a doublet of which the lower band is nonspecific, as previously reported.⁷  The upper band of the doublet is Snk/Plk2 as described.⁷  (D) Snk/Plk2 mRNA is detected in primary B lymphocytes but not in primary BL. RT-PCR was performed as described in “Materials and methods.” Mr indicates 100-bp molecular weight markers; lanes are as shown. (E) Real-time RT-PCR analysis of Snk/Plk2 expression in primary BL and primary B cells. Lanes are as shown. Data shown are relative expression levels normalized against the internal control gene ARPO and bars indicate SDs. The results are derived from 3 independent experiments.