SMAD1⁻DLBCL patient cells respond to DAC treatment in a patient-derived xenograft model. (A) SMAD1 and S1PR2 expression in CD19⁺ primary DLBCL cells, as determined by qRT-PCR; SU-DHL-6 cells are shown as positive control. Percentages of human CD45⁺ cells in the spleen (B) and bone marrow (C) of MISTRG6 mice that were injected with primary DLBCL cells and treated with 0.25 mg/kg DAC for 3 cycles of 5 days per week. (D) Spleen weights at the end point. (E) Representative FACS plots showing frequencies of human and mouse CD45⁺ cells in the spleens. In panels B-D, each symbol represents 1 mouse and horizontal lines represent median values; data are pooled from 3 independent experiments. (F) Hematoxylin and eosin–stained sections of spleens from representative mice treated or not with DAC. Scale bars, 100 μm. (G) SMAD1 immunohistochemical staining of representative mice treated or not with DAC. Scale bars, 100 μm. *P < .05, **P < .01, Mann-Whitney U test. n.d., not detectable.