However, individual SERPINE1-positive cells in the invasive margin may correspond to the 5-ALA-positive tumor subpopulation expressing SERPINE1 at a high level (Figure 4F), but existing as a minority population within the total unsorted tissue sample, with a predominance of low/absent SERPINE1 expression in normal brain harboring these invasive GBM cells. Here, SERPINE1 is linked to glioblastoma.