BRAF and melanoma: To test this, we generated “high-density” PC9 persister cells and BRAF and MAPK kinase inhibitor–derived BRAF V600E A375 melanoma persister cells by treating with lower drug concentrations for 10 days, resulting in fully confluent persister cells, and found that high-density persister cells remain selectively sensitized to ferroptosis versus density-matched parental cells of equal or lower confluency (fig.