Induction of bPRP-1 in Matrigel cultured BT cell lines. (A) An immunofluorescent image displaying anti-bPRP-1 staining of BT-1, BT-C, and BT-K cells, which were cultured in collagen-coated wells or by on-Matrigel culturing for 8 days. Nuclear DNA was stained with Hoechst 33342. Bar = 50 μm. (B) The percentages of bPRP-1-positive cells in the collagen-coated (black bar) and Matrigel cultures (white bar). Three pictures were taken of random locations in each sample. The mean percentage of bPRP-1-positive cells was calculated from three different experiments. The bar graph shows mean ± SEM values. The asterisks indicate a significant difference compared with the control (P < 0.05).