Figure 8.
C-Myb is not required for G2/M gene expression. (A) C-Myb does not bind to the endogenous G2-regulated promoters. T98G cells were released from serum starvation and samples were harvested at quiescence (Q), or at 9, 12, 15, 18, 21, and 24 h after serum addition for ChIP analysis using the indicated antibodies. One E2F-regulated G1/S gene (cdc6) and a non-E2F-regulated gene (albumin) were used as controls. (B) Western analysis of the above C-Myb ChIP samples. The mouse monoclonal C-Myb antibody (C-2; Santa Cruz) was used to probe the Western blot. (C) C-Myb is not required for G2/M gene expression. Western analysis of several G2/M genes (cdc2, cyclin A2, and cyclin B1), G1/S genes (E2F3, B-Myb, DHFR, and cdc6), and a noncycling gene SP1 using cell extracts from asynchronously growing T98G cells transfected with either a control luciferase siRNA or a C-Myb siRNA. Cell lysates were prepared 48 h after siRNA transfection. NS=nonspecific band.