Marching cubes has long been employed as a standard indirect volume rendering approach to extract isosurfaces from 3D volumetric data. This paper presents a GPU-friendly MC implementation. Besides the cell indexing, we propose to calculate vertex and normal interpolations by precomputing the expensive equations and looking up these values during runtime. Upon a commodity GPU, our implementation can rapidly extract isosurfaces from a high-resolution volume and render the result. With the proposed parallel marching cubes algorithm, we can naturally generate layer-structured triangles, which facilitate the visualization of multiple-layer translucent isosurfaces without performing computational expensive sorting. The algorithm extracts and draws triangles, in a layer by layer fashion, from back to front.