GOLGA1 and precursor B-cell acute lymphoblastic leukemia: Furthermore, immunofluorescence revealed that intracellular Sig15 strongly colocalized with the Golgi apparatus and trans-Golgi network (TGN) marker, Golgin-97 (Fig. 3B), suggesting retention of Sig15 in the Golgi apparatus in B-ALL cells with limited trafficking to the membrane along the TGN.