Fig. 2: Functional significance and mechanism governing the downregulation of CD48 by CBFB-SMMHC.

a–d Cytotoxicity assays. ³⁵S-labeled U937 cells expressing CBFB-SMMHC or an empty vector were pre-incubated with or without anti-CD48 or control mAb and then incubated with YTS eco cells (a, b) or with primary NK cells (c, d). The effector to target (E:T) ratios were 50:1 (b), 2.5:1 (d), or indicated on the x-axis (a, c). Error bars represent the standard deviation of triplicates. One representative experiment is shown out of three performed. (e) Flow cytometry analysis of CD48 level in cells expressing two deletion mutants of CBFB-SMMHC (both in blue histograms): Δ95 (left) and ΔACD (right) in parallel to staining of cells expressing the WT CBFB-SMMHC protein (black histograms) or an empty vector (gray histograms). The analysis was performed with gating on GFP+ cells. Gray-shaded histogram, background staining with an isotype-matched control antibody. One representative experiment is shown out of two performed. f Flow cytometry analysis of CD48 expression in U937 cells transduced with CBFB-SMMHC and treated with HDAC inhibitors (HDACi). Cells transduced with an empty vector were treated with a solvent control (gray lines); cells transduced with CBFB-SMMHC were treated with a solvent control (black lines) or with two different HDACi (blue lines): mocetinostat and entinostat. Gray-shaded histogram, background staining with an isotype-matched control antibody. The figure shows one representative experiment out of two performed. g Expression of CD48 in normal bone marrow samples (left) and in bone marrow samples of AML patients expressing CBFB-SMMHC (right) as determined by qRT-PCR. Black line represents the mean value. In all figure panels, *P < 0.05, **P < 0.01, ***P < 0.001, Student’s t-test