CDKN1B and glioblastoma: The addition of thrombin to cell cultures resulted in univocal and stable downregulation of p27 expression by 6 h (0.2 and 0.4‐fold decrease, P = 0.015 and P = 0.006 compared to unstimulated breast and glioblastoma cells, respectively; Fig. 2A and B, right panels) and the induction of cyclin D1 expression (up to 3.2‐fold increase; P = 0.028 and P = 0.044 compared to unstimulated breast and glioblastoma cells, respectively).