TNK1: tyrosine kinase, non-receptor, 1. TNK1 is a nonreceptor tyrosine kinase(NRPTK). These kinases, like members of the SRC (MIM 190090) and JAK (see MIM 147795) families, mediate intracellular signaling downstream of receptor activation.Tnk1 is a ubiquitously expressed 47-kDa protein with autotyrosine kinase activity that is developmentally regulated during embryogenesis. Tnk1 is also upregulated following IL3 withdrawal from factor-dependent murine NSF/N1.H7 cells that undergo apoptosis, suggesting a role in growth inhibition. Data support a negative regulatory role for Tnk1 in regulating the Ras-Raf1-MAPK growth pathway by a mechanism that requires its autotyrosine kinase activity.