Moreover, only mice lacking SK1 in bone marrow demonstrated significant splenomegaly with DSS treatment (Figure 1B), likely indicating that SK1 in hematopoietic-derived cells may be necessary for egress of lymphocytes from the spleen in DSS-induced colitis, as S1P has been implicated in lymphocyte egress [23]. This evidence concerns the gene SPHK1 and Splenomegaly.