PIK3CD and melanoma: AKT1 has been shown to promote melanoma brain metastasis through regulation and activation of proteins involved in focal adhesion.15 Molecular profiling of patient-matched intracranial and extracranial metastases revealed an overall similarity in the majority of molecular features of intracranial and extracranial metastases.16 Nevertheless, intracranial metastases demonstrated increased expression of activation-specific proteins in the PI3K–AKT pathway compared to extracranial metastases suggesting a critical role for activation of the PI3K–AKT pathway.