SLAP also known as Src-like-adapter protein 1 is a 276aa containing adapter protein, functioning as a negative regulator of T-cell receptor (TCR) signaling. SLAP belonging to the SRC family of cytoplasmic tyrosine kinases contains a SH2 domain and a SH3 domain. This cytoplasmic protein colocalizes with endosomes and is known to inhibit T-cell antigen-receptor induced activation of nuclear factor of activated T-cells. It acts as a negative regulator of positive selection and mitosis of T-cells. SLAP may act by linking signaling proteins such as ZAP70 with CBL, leading to a CBL dependent degradation of signaling proteins. Expression of SLAP is weak in heart, adult brain, placenta, liver, skeletal muscle, kidney and pancreas but is high in lung and fetal brain.