POSTN and sarcoma: Crucially, however, this shared stress response manifested in lineage‐distinct oncogenic trajectories: T cells exhibited thymic developmental arrest through Notch1 activation and Rag1/2 suppression, culminating in spatially‐confirmed lymphoma subtypes; B cells demonstrated pre‐B receptor hyperactivation with unique antigen‐presentation alterations; fibroblasts developed sarcoma via mesenchymal pathway activation (Ddit4/Postn overexpression); while epithelial cells underwent tissue‐specific EMT programs.