FAP and malignant peripheral nerve sheath tumor: Single-cell analysis showed FAP expression in MPNST tumor cells and cancer-associated fibroblasts, with the highest levels in neural crest-like tumor subpopulations previously linked to adverse prognosis; pseudotime analysis indicated decreasing FAP expression along trajectories toward Schwann cell precursor-like states linking FAP expression to a more primitive, dedifferentiated tumor cell state.