The retinoblastoma gene family RB1, p107 and RB2/p130 cooperate to regulate cell cycle progression through the G1 phase of the cell cycle. Previous data demonstrated that RB2/p130 inhibits proliferation of the glioblastoma cell line T98G, which is resistant to the growth suppressive effects of both RB1 and p107, and that RB2/p130 gene overexpresion induces astrocyte differentiation. We screened by single-strand conformation polymorphism and sequence analysis the structure of exons 19 through 22 of the RB2/p130 gene, which encodes the B domain and C terminus, in a series of 42 glioblastomas (32 primary and 10 secondary). Sequence variations were identified in one tumor, suggesting that mutation inactivation of RB2/p130 is a rare event in glioblastoma.