BRAF and melanoma: Melanoma cells and fibroblasts were enriched from tumors treated with 3‐day BRAF/MEKi (regressing) and tumors treated with 14‐day BRAF/MEKi (residual disease) using negative selection by depletion of endothelial cells, hematopoietic nucleated cells, red blood cells, and platelets.[14] Enrichment was validated by flow cytometry (Figure 1B,C; gating strategy and quantification plot in Figure S1B,C, Supporting Information).