Although the outcome of patients with acute myeloid leukemia (AML) has improved in the past decades, the overall survival is below 50% [1, 2] and there is still an unmet need for the development of new therapeutic strategies. Here, we aimed to identify functional vulnerabilities in AML and investigated the therapeutic potential of target structures involved in proteostasis, cell polarity and RNA-binding molecular pathways. We determined that genetic deletion of the cell fate determinant and polarity regulator Scribble delays AML development, however, its deletion also seems to affect the proliferative capacity of normal hematopoietic cells, lowering its value as a therapeutic target. In contrast, inactivation of YBX1 (a pleiotropic protein with DNA/RNA binding capacity that excerpts post-transcriptional control on its targets) and PSMB8/LMP7 (a catalytic subunit of the immunoproteasome multiprotein complex that belongs to the ubiquitin-proteasome system (UPS)) inhibit leukemic cells without influencing normal hematopoietic stem and progenitor cell function, establishing these targets as potential novel therapeutic strategies against AML. Genetic deletion of YBX1 caused reduced proliferation and colony forming capacity in leukemic cells independent of the oncogenic driver mutation and delayed AML development in vivo. The role of Ybx1 in leukemia maintenance was investigated using a conditional knockout model, confirming the functional requirement of Ybx1 in AML maintenance. Mechanistically, YBX1 recruited oncogenic transcripts to polysomes, increasing their translation. Displacement of these transcripts from polysomes after YBX1 deletion decreased their protein expression. Genetic and pharmacologic inhibition of PSMB8/LMP7 decreased proliferation and colony forming capacity selectively in KMT2A (MLL)-rearranged leukemic cells. In vivo treatment with a PSMB8/LMP7 inhibitor delayed disease development in KMT2A-rearranged leukemic mice or patient derived xenografts (PDX). We identified the transcriptional corepressor BASP1 as a functional effector of the immunoproteasome. BASP1 was enriched after PSMB8/LMP7 inhibition and it was found binding to KMT2A-target genes. Moreover, pharmacologic inhibition of PSMB8/LMP7 led to decreased expression of bonafide KMT2A-fusion target genes and enrichment for genes deregulated by inhibitors of the KMT2A complex partners DOT1L and MEN1. This prompted us to investigate a potential synergism between MEN1 inhibition and immunoproteasome inhibition. Combination treatment in AML cells revealed decreased proliferation in vitro and increased survival in vivo as compared to the single treatments, demonstrating the therapeutic potential of combining immunoproteasome and MEN1 inhibitors.