STAT5 regulates CD48 expression in IL2-dependent ATLL cells. (A-B) Normalized cell surface CD48 expression by flow cytometry on (A) KK1 cells treated with compound library (2.5 μM) for 24 hours and (B) ATLL cell lines treated with ruxolitinib (2.5 μM) or dimethyl sulfoxide for 24 hours. (C) Immunoblot analysis of pSTAT3, STAT3, pSTAT5B, and STAT5B in ATLL cells treated with ruxolitinib (2.5 μM) for 24 hours. (D) Immunoblot analysis of CD48, JAK1, JAK2, JAK3, TYK2, STAT3, and STAT5B in sgJAK1, sgJAK2, sgJAK3, sgTYK2, sgSTAT3, and sgSTAT5B-transduced KK1 cells. The quantification of CD48 immunoblot bands, normalized to GAPDH and compared with sgAAVS1 control cells, is shown below the CD48 immunoblot. (E-F) Normalized cell surface CD48 expression on (E) sgJAK1, sgJAK2, sgJAK3, and sgTYK2, and (F) sgSTAT3- and sgSTAT5B-transduced KK1 cells. (G) Normalized cell surface CD48 expression by flow cytometry on sgSTAT5B-transduced ATLL cells. Error bars represent the SEM of replicates. ∗P < .05, ∗∗P < .01, and ∗∗∗P < .001, Welch 2-sample t-test.