Ca2+ (Calcium) plays a major role in life and death within T-Cells. Elevation of intracellular free Ca2+ is one of the key triggering signals for T-Cell activation by antigen. The binding of antigen, MHC Class-II (Major Histocompatibility Complex Class-II), to the TCR-CD3 (T-Cell Antigen Receptor)-CD3 (CD3 Antigen) triggers the recruitment of a series of tyrosine kinases and substrates to the TCR/CD3/CD4 (CD4 Antigen) Complex, ultimately resulting in the phosphorylation and activation of PLC-Gamma1 (Phospholipase-C-Gamma1). PLC-Gamma1 cleaves PIP2 (Phosphatidylinositol 4,5-bisphosphate) in the plasma membrane to generate DAG (Diacylglycerol), which activates PKC (Protein Kinase-C) and IP3 (Inositol 1,4,5-trisphosphate), that causes entry of Ca2+ to cytosol from two sources: the ER (Endoplasmic Reticulum) and the extracellular space. IP3 generated subsequent to TCR-CD3 stimulation [...]