Fig. 4. POPX2 blocks the nuclear translocation of MAL. (A) HA-tagged MAL was co-transfected with GST-POPX2 or GST control vector into NIH3T3 cells. The cells were fixed and immunostained with antibodies to the tags to detect the location of MAL after growing in media containing 0.5% serum. The top panels show that HA-MAL was localized in the cytoplasm in the presence of GST-POPX2. The bottom panels show the nuclear location of HA-MAL in the absence of POPX2. DAPI stained the nuclei. (B) Various GST-tagged POPX cDNA constructs were co-transfected with HA-MAL and immunostained as in A. The transfected cells were scored for MAL nuclear localization. Lane 1: HA-MAL + GST control vector; 2, HA-MAL + GST-POPX1; 3, HA-MAL + GST-POPX2; 4, HA-MAL + GST-POPX2m; 5, HA-MAL + GST-POPX2N; 6, HA-MAL + GST-PPc; 7, HA-MAL + GST-PPm. Each transfection was repeated three times and approximately 100 transfected cells were scored per transfection. Scale bar: 25 µm.