... BTK–SYK and ITK–SYK fusion proteins lead to differential phosphorylation levels of the fusion proteins themselves, as well as the downstream adapter proteins SLP76 and BLNK, in 293T and COS7 cells. ... ª 2011 FEBSMINIREVIEWTEC family kinases in health and disease – loss -of- function of BTK and ITK and the gain -of- function fusions ITK–SYK and BTK–SYKAlamdar Hussain1,2,*, Liang Yu1,3,*, ... sus-ceptible cells at multiple levels [62]. In resting humanCD4+T cells, the expression of ITK is extremely low and often undetectable in immunoblot analysis. Theactivation of CD4+cells, however,...