Using data from over 100,000 malignant and non-malignant cells from 15 human brain metastases, UCSF researchers have revealed two functional archetypes of metastatic cells across 7 different types of brain tumors, each containing both immune and non-immune cell types. Their findings, published the February 17 issue of Cell, provide a potential roadmap for metastatic tumor formation that could be used to design therapies to improve the treatment of metastasized patients.