Bruton’s Tyrosine Kinase (BTK) is a 76kDa non-receptor Tec kinase that plays numerous diverse roles in B-cell development, immunity, autoimmunity, infection, and cancer. From stem to stern, it consists of an N-terminal plekstrin homology (PH) domain, a TEC homology (TH) domain, two SRC homology (SH2 and SH3) domains, and a C-terminal kinase domain. Unlike SRC,