GEOapplication/xmlftp://ftp.ncbi.nlm.nih.gov/geo/series/GSE319nnn/GSE319183/primaryOK200TranscriptomicsHomo sapiensExpression profiling by high throughput sequencinghttps://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE319183GEOGSEfalseDynamic expression of CD9 protein in T-cell acute lymphoblastic leukemia [bulk RNA-seq]T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy affecting both children and adults. Given its persistently poor prognosis, there is a critical need to identify additional factors involved in T-ALL oncogenesis and progression. CD9, a membrane protein of the tetraspanin family implicated in diverse cellular processes, has been associated with prognosis in several cancers, yet its role in T-ALL remains poorly understood. In this study, using first a mouse model, we found that CD9 overexpression is associated with leukemic T cells that have migrated outside the thymus into peripheral tissues. Then, analysis of a human T-ALL cohort shows that CD9 expression is heterogeneous, tends to increase at relapse and is enriched in the TAL1⁺ molecular subtype. We further demonstrate that CD9⁺ cells display enhanced migratory capacity compared with CD9⁻ counterparts, and that CD9 levels affect extracellular vesicle biogenesis. Altogether our findings support a role for CD9 in T-ALL leukemogenesis and highlight its potential involvement in relapse.2026/04/27GSE319183GSM9513248GSM9513247GSM9513246GSM9513245GSM9513244GSM9513243GSM9513242GSM9513252GSM9513241GSM9513251GSM9513250GSM951324934281319183Homo sapiens