The CellSensor® STAT6-bla RA-1 Cell Line contains a beta-lactamase reporter gene under control of the STAT6 response element stably integrated into Ramos-1 (RA-1) cells. This cell line is a clonal population isolated by flow cytometry in response to interleukin-4 (IL-4). This cell line has been tested for assay performance under variable conditions, including DMSO concentration, cell number, stimulation time, and substrate loading time, and validated for Zfi-factor and EC50 concentrations of IL-4. Additional data using alternate stimuli are also available. IL-4 is known to induce the growth and differentiation of B cells, T cells, myeloid cells, and hepatocytes. In B cells, IL-4 acts as a co-mitogen to induce the expression of the Fc receptor for IgE and also major histocompatibility complex (MHC) class II molecules, and it stimulates the transcription of immunoglobulin heavy-chain germline IgE and IgG1 genes, leading to class switching. IL-4 function is mediated by the IL-4 receptor complex, which activates Jak1 and Jak3 tyrosine kinases. STAT6 is recruited to the IL-4R complex and is subsequently phosphorylated by the Jak kinases. This causes STAT6 to dimerize and translocate to the nucleus where it binds to specific sequences on IL-4-responsive genes. Optimal transcription response of IL-4-inducible promoters requires two Th2-mediated stimuli, CD40 ligand and IL-4. CD40 ligand is a protein expressed on the surface of T cells. It regulates B cell function by engaging CD40 on the B cell surface, leading to signaling through NFκB. Academic and non-profit customers, please inquire for special pricing.