CA9 and glioblastoma: Representative images of IHC findings for S100A4, NMIIA, HIF-1α, and CA9 in GBMs are illustrated in Fig. 1A. Nuclear/cytoplasmic immunoreactivity for S100A4, nuclear immunoreactivity for HIF-1α, and cytoplasmic immunostaining for NMIIA and CA9 were frequently found in GBM cells that were mainly located at both non-Ps and Ps (-associated) perinecrotic lesions.