FIG. 6.
Nuclear and cytoplasmic distribution of PBX species for endocrine and exocrine pancreatic cells. (A) 266-6 nuclear extract contains PBX1b and PBX2, whereas RIN38 nuclear extract contains only PBX2. Western analyses of nuclear extracts (30 μg of total protein/lane) from 266-6 or RIN38 cells were probed with antibodies specific to PBX1a, PBX1b, PBX2, and PBX3. IVT PBX species (0.5 μl) present in each panel demonstrate the specificity and reactivity of each antibody. (B) PBX1b is present in three different exocrine cell lines but is absent in three endocrine cell lines. Western analyses of nuclear extracts (30 μg of total protein/lane) from the acinar cell lines AR42J, ARIP, and 266-6 and the β-cell lines RIN38, βTC-3, and Ins1, as well as a control (Jurkat pre-B) cell line, were probed with antibodies specific for PBX1. (C) Cytoplasmic versus nuclear localization of PBX species in 266-6 acinar and RIN38 endocrine cells. Cytoplasmic and nuclear extracts (30 μg of total protein/lane) probed with antibodies specific to PBX1, PBX2, and PBX3 detected PBX1b only in the 266-6 nuclear compartment, PBX2 in both the nuclei and cytoplasm of both the endocrine and acinar cell lines, and PBX3b only in the cytoplasm of the two cell lines. Numbers on the left in each panel are molecular masses in kilodaltons.