BloodSpot analysis showed increased CDC42 messenger RNA expression in primary human AML across cytogenetic subtypes in comparison with normal HSC/P controls. CDC42 expression was increased in t(11q23)/MLL rearranged AML compared with HSC, multipotential progenitor (MPP), common myeloid progenitor (CMP), granulocyte monocyte progenitor (GMP), and megakaryocyte-erythroid progenitor (MEP) subsets. *P < .01; ** P < .001. A similar trend was seen across cytogenetic subtypes of AML, including t(15;17), inv(16), t(8;21), and complex karyotype. BloodSpot is a curated database of publicly available gene expression datasets. AML samples came from the Microarray Innovations in Leukemia study headed by the European Leukemia Network and sponsored by Roche Molecular Systems, Inc. The normal hematopoietic subsets were from multiple studies. Platforms included Affymetrix Human 133U plus 2, Affymetrix Human 133UA, and Affymetrix Human 133UB chips (http://servers.binf.ku.dk/bloodspot/).