MAPK3 and systemic lupus erythematosus: RASGRP1 is extremely important for the development of conventional αβ T cells but not the meager population of γδ T cells.193–195 However, it is important for the activation of both types of T cell population as well as for the expression of IL-17.195 RASGRP1 deficiency can cause defects in the activation of various signaling pathways, such as RAS–MAPK–ERK1/2, mTOR, and PI3K/AKT.193,196 Moreover, abnormal expression of both RASGRP1 and RAS was described in T cells of systemic lupus erythematosus (SLE) patients, thereby implicating the involvement of this pathway in the generation of SLE.197