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The Krüppel-like family of transcription factors (KLF) plays critical roles in human development and is associated with cancer pathogenesis. KLF5 has been shown to promote cancer cell proliferation and tumorigenesis, and to be genomically amplified in cancer cells. We recently reported that the KLF5 gene is also subject to other types of somatic coding and noncoding genomic alterations in diverse cancer types. Here we show that these alterations activate KLF5 by three distinct mechanisms. 1) Focal amplification of super-enhancers activates KLF5 expression in squamous cell carcinomas. 2) Missense mutations disrupt KLF5-FBXW7 interactions to increase KLF5 protein stability in colorectal cancer. 3) Cancer type-specific hotspot mutations within a zinc-finger DNA binding domain of KLF5 change its DNA binding specificity and reshape cellular transcription. Utilizing data from CRISPR/Cas9 gene knockout screening, we reveal that cancer cells with KLF5 overexpression are dependent on KLF5 for their proliferation, suggesting KLF5 as a putative therapeutic target.