The function of KLHL15 (kelch like family member 15, Ensembl gene identifier ENSG00000174010) is as follows. Substrate-specific adapter for CUL3 E3 ubiquitin-protein ligase complex (PubMed:14528312, PubMed:27561354, PubMed:35219381). Acts as an adapter for CUL3 to target the serine/threonine-protein phosphatase 2A (PP2A) subunit PPP2R5B for ubiquitination and subsequent proteasomal degradation, thus promoting exchange with other regulatory subunits (PubMed:23135275). Acts as an adapter for CUL3 to target the DNA-end resection factor RBBP8/CtIP for ubiquitination and subsequent proteasomal degradation (PubMed:27561354, PubMed:35219381). Through the regulation of RBBP8/CtIP protein turnover, plays a key role in DNA damage response, favoring DNA double-strand repair through error-prone non-homologous end joining (NHEJ) over error-free, RBBP8-mediated homologous recombination (HR) (PubMed:27561354, PubMed:35219381). {ECO:0000269|PubMed:14528312, ECO:0000269|PubMed:23135275, ECO:0000269|PubMed:27561354, ECO:0000269|PubMed:35219381}.