PDCD4 and glioblastoma: Dorrello et al. (39) previously showed that in starved T98G glioblastoma cells, Pdcd4 was ubiquitylated/degraded following serum starvation/replenishment through the SCFβTrcp-dependent pathway, which required the phosphorylation of Pdcd4 at serines 67, 71, and 76.