ARHGEF3 and B-cell non-Hodgkin lymphoma: ARHGEF3 (or XPLN, exchange factor found in platelets, leukemic, and neuronal tissues) was identified as RhoGEF (Rho guanine nucleotide exchange factor) for Rho GTPases through an expressed sequence tag) database search, using the diffuse B-cell lymphoma (Dbl) homology (DH) domain query in the BLASTN system (Thiesen et al., 2000).