POU3F2 and melanoma: Attempts to prospectively isolate distinct transcriptional states have been unreliable, preventing the direct functional comparison of live cells.12–20 For example, pioneering studies on phenotype switching in melanoma introduced a dichotomy between invasive and proliferative cell states, distinguished by the expression of the BRN2 and MITF transcription factors, respectively.21–25 Although conducted on bulk cell populations, one theoretical concept that emerged from these studies was that of bidirectional phenotype switching of a single cell.