TYK2 and fibrosarcoma: To strengthen these findings, we studied TYK2-null fibrosarcoma 11,1 cells [18] transfected with TYK2-V362, TYK2-F362, variant TYK2-A928V, variant TYK2-P1104A (these latter in the F362 background) and the bona fide kinase-dead TYK2-K930R [19].