NFKBIA and sarcoma: Thymic T‐cell lymphomas are born from proliferating double‐positive T cells; peripheral T‐cell lymphomas derive from immune‐activated T cells and NKT cells; B‐cell lymphomas derive from proliferating pre‐B cells; sarcomas derive from pan‐tissue Nfkbia+ fibroblasts; epithelial carcinomas are traced back to secretory AV cells in the mammary gland.