Figure 3.

Localization of myosin IIA and IIB in normal rat brain and in the PDGF-driven brain tumor model. (A) Low power micrograph showing the distribution of myosin IIA (red) in the contralateral, normal hemisphere of a tumor-bearing rat. The paucity of staining for myosin IIA is consistent with the immunoblot results in Figure 2B. (B) Low power micrograph showing the distribution of myosin IIB (red) in the contralateral, normal hemisphere. Myosin IIB is diffusely distributed in cortex and white matter in the uninvolved hemisphere. (C) Low power micrograph of the tumor-bearing hemisphere, stained with antibody to myosin IIA. There is increased staining for myosin IIA in the tumor (T) compared with the surrounding brain tissue, cortex (CX), striatum (Str) and corpus callosum (CC). Particularly high levels of staining are seen in the tumor vessels (white arrow). Bar, 1 mm. (C′–C‴) High-power micrographs showing immunostaining for myosin IIA (red) in a GFP-expressing cell (green) that is infiltrating the cortex. Nuclei are stained blue with DAPI. Bar, 10 μm. (D) Low-power micrograph of myosin IIB (red) in the tumor-bearing hemisphere. Increased levels of myosin IIB immunoreactivity are seen in the tumor vessels (white arrow), whereas in most of the tumor (T), the levels of myosin IIB immunoreactivity are similar to that of the surrounding brain tissue. (D′–D‴) High-powered micrograph showing myosin IIB immunoreactivity (red) in a GFP-expressing cell (green) infiltrating the cortex. Nuclei are stained blue with DAPI. The white arrow in C and D points to tumor vessels surrounding an area of necrosis (N).