P27kip1levels remain high as observed in pretumor cells of tumors from Cks1 knockout LMP2A/λ-MYC and λ-MYC mice. (A) Representative immunohistochemical analysis of lymph node tumors from 3 to 6 mice of each genotype stained with hematoxylin and eosin, B220, p27kip1, and Thr187-phosphorylated p27kip1, using an EVOS XL core microscope with ×40 magnification. Insets are tumors imaged by a Nikon Eclipse E600 microscope with ×100 magnification and oil immersion. (B) Percentage of lymphoma cells with intense nuclear staining of Thr187-phosphorylated p27kip1 in total lymphoma cells per microscopic field (×40 magnification) analyzed by ImageJ software (National Institutes of Health). (C) Immunoblots of p27kip1 and MYC expression in tumor cells. (D) P27kip1 and (E) MYC expression were normalized to Gapdh (a loading control). Data represent the mean ± standard deviation. ***P < .001, ****P < .0001, calculated by 1-way ANOVA with post hoc multiple comparison tests.
