Purified BMP-4 facilitates enhanced replication of GLV-1h189 in GBM CSCs. A) GLV-1h189 infection of GBM CSCs in the absence (top panels) or presence (lower panels) of BMP-4 at 9 dpi. In the presence of BMP-4 the majority of the spheroids are broken down into cell clusters that are either infected or have a differentiated appearance. (Magnification 4X). B) BMP-4 enhances replication of GLV-1h189 in GBM CSCs as indicated by RLuc expression (relative light units, RLUs) at 9 dpi. GLV-1h189 in the presence of BMP-4 showed heightened replication that ranged from approximately 4–50 fold higher compared to GBM CSCs infected with GLV-1h189 alone at MOIs less than 2. An MOI of 0 is cells only, uninfected background control.