Triple-negative breast cancer (TNBC) is one of the deadliest types of breast cancer. Its mechanisms are complex, and they differ among patients, making TNBC difficult to treat. To search for new treatment targets, researchers recently investigated the potential role of RBCK1, an enzyme known to promote tumor growth and hormone therapy resistance in other subtypes of breast cancer. They found that RBCK1 was upregulated in TNBC tissue compared to normal breast tissue. However, in contrast to its effects in other subtypes, RBCK1 improved survival in TNBC. Specifically, it reduced cancer cell proliferation and metastatic behaviors in TNBC cells in vitro and in a mouse TNBC model in vivo. RBCK1 exerted these effects by binding to the protein YAP and targeting it for degradation consequently reducing the expression of the YAP target protein Hippo. Although further research is needed, these unexpected findings reveal that RBCK1 has different functions depending on the breast cancer subtype and identify this enzyme as a potential target for TNBC treatment.