Carabin inhibits B-lymphoma cell proliferation. (A) Downregulated Carabin expression in DLBCL tissues. Carabin protein was analyzed in 18 DLBCL specimens, 4 benign tissues as control. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was the immunoblot loading marker. (B) Overexpression of Carabin suppresses B-lymphoma cell proliferation. Stable expression of green fluorescent protein (GFP)-Carabin was detected by western blot (WB) in SU-DHL-6 cells. A cell growth assay was carried out over a 5-day culture period and living cells were detected by Alarma blue every 24 hours. Points, mean (n = 6); bar, standard deviation (SD); *P < .05; **P < .01; ***P < .001. Knockdown of Carabin promotes B-lymphoma cell proliferation. Knockdown of Carabin was carried out by lentivirus in (C) GCB-DLBCL cell lines, SU-DHL-4 (left), and SU-DHL-6 (right) cells; (D) ABC-DLBCL cell lines, NU-DUL-1 (left), and SU-DHL-2 (right). Cell growth assays were analyzed as described above. Points, mean (n = 6); bar, SD; *P < .05; **P < .01; ***P < .001. (E) The resected tumors from individual nude mice. Carabin knockdown and control SU-DHL-4 stable cells were injected into 2 nude mice groups, respectively. Seven mice were used in each group. (F) The tumor volume of the xenografts. Points, mean (n = 7); bar, SD; ***P < .001. (G) The tumor weight of the xenografts after dissection. Scatter plot, mean (n = 7); bars, SD; ***P < .001. (H) Immunohistochemical analysis of Ki-67 (top) and p-Erk (bottom) in the xenograft tumor tissues (hematoxylin and eosin stain; scale bar, 50 μM). C+, cells stably expressing GFP-Carabin; Con, control cell; NC, control cell; shC, cells stably expressing Carabin-specific shRNA.