GLK is a member of the STE20 family of serine/threonine protein kinases and contains N-terminal catalytic domain and C-terminal regulatory domain. GLK is upstream of the MEKK1 target and is stimulated by UV radiation and TNF- and can lead to the activation of the JNK signaling pathway. GLK can directly activate PKC-θ during TCR signaling and people with systemic lupus erythematosus show considerable enhanced GLK expression and activation of PKC-θ and the kinase IKK in T cells (1). GLK can act as a pro-apoptotic kinase which orchestrates activation of BAX via the concerted posttranscriptional modulation of PUMA, BAD, and BIM (2).