In a new study published in Biophysical Journal, TIME Lab researchers led by Killian Onwudiwe (former post-doctoral fellow) and Julian Najera (Bioengineering PhD student) have discovered that there are striking viscoelastic similarities between glioblastoma cells and astrocytes, their healthy brain cell counterparts. These findings from primary brain tumors are contrary to results from extracranial tumors (e.g., in breast cancer), where cancer cells are often softer and less viscous than their normal cellular counterparts (e.g., breast epithelial cells), and are more likely to metastasize away from the primary tumor. Although it has been shown previously that tissue-level mechanical properties often differ between primary brain tumors and the surrounding brain, our study suggests that those differences are likely mediated by variations in extracellular matrix rather than changes in cellular viscoelasticity. Our study also raises an unanswered question: does this lack of viscoelastic advantage explain in part why glioblastoma rarely metastasizes outside of the brain?