CSK inhibitor 13 (SI-3, CSK-IN-1) is a potent, selective inhibitor of C-terminal Src kinase (CSK) with IC50 of <3 nM in HTRF assays, increases ZAP-70 phosphorylation in Jurkat cells with EC50 of 260 nM, does not inhibit LCK.
SI-3 inhibits recombinant LYN protein with a half-maximum inhibitory concentration (IC50) of 56.7 nM.
SI-3 induces LYN degradationm which is ubiquitin dependent.
CSK inhibitor 13 increases IL-2 secretion in CHO cells expressing OKT activate T cells proliferation.
CSK inhibitor 13 reduces inhibitory LCK phosphorylation in vivo upon oral dosing and shows the ability to enhance T cell activation in response to antigen stimulation.

CSK inhibitor 13 increases IL-2 secretion in CHO cells expressing OKT activate T cells proliferation.
CSK inhibitor 13 reduces inhibitory LCK phosphorylation in vivo upon oral dosing and shows the ability to enhance T cell activation in response to antigen stimulation.