Recent work has identified the pro-apoptotic gene APAF1 as a likely target for repression by HDAC2, providing a specific mechanism for both HDACi efficacy and resistance in HDAC2 mutant cells, where HDACi does not appreciably alter APAF1 levels (Hanigan et al., 2008).
However, we also observed many baz and baz mutant cells where Crb immunostaining appeared normal (Fig. 7C C″″, arrowheads).
The mutated protein becomes trapped in the nuclei of mutant cells, where it associates with RNA-binding factors, including muscleblind-like (MBNL) proteins, disrupting splicing.
In this light, it is interesting to note that we could also detect no decrease in the amount of γ-tubulin recruited to centrosomes in Dgrip75 mutant cells, where the formation of the γ-TuRC is disrupted (Vogt et al., 2006).
Square packing is present at the midzone of anaphase B spindles in both genetic backgrounds, but the tight hexagonal packing nearer the poles of anaphase B spindles was not observed in cdc25.22 mutant cells, where a more variable transverse architecture was present.
Time course studies were performed with wild-type and c4 mutant cells where both were dosed with either 10 nM TCDD (provided by S. Safe, Texas A&M University, College Station, TX) or DMSO (Sigma, St . Louis MO) vehicle and harvested at 1, 2, 4, 8, 12, 24 or 48 hrs.
To test this postulation, we further studied the inhibitory effects of thiacremonone on the DNA-binding activity of NF-κB and NO generation in p50 mutant cells (C62S), where the cysteine residue at 62 of p50 was replaced by serine.
Interestingly, 1 μM concentration of MTA promoted an increase in the number of colonies in 37-31E cells, with no detectable effects in the other of cell lines tested except for the BRAFV600E mutant cell line Colo829 where 1 μM of MTA totally suppressed the colony formation.
In agreement with its profile of biological activities, vemurafenib displayed consistent inhibitory effects exclusively on the BRAF-mutant HROC24 cells, where it efficiently blocked phosphorylation of MEK1/2 and ERK1/2) at concentrations that also significantly diminished cell growth.
Using lig4Δ mutant cell as a host strain, where the non-homologous end joining (NHEJ) activity is deficient, the efficiency was increased >95%.
