Furthermore, cells lacking CtBP fail to undergo mitotic arrest induced by spindle toxins, indicating a spindle checkpoint defect.
On bleomycin treatment, SPAC607.02cΔ cells arrested in the cell cycle, similar to wild-type cells, indicating an intact checkpoint response.
Strong reduction of CENP-H resulted in a slightly reduced CENP-C level at the kinetochores and normal localisation of hBubR1, indicating a functional mitotic checkpoint at the hBubR1 protein level.
In agreement with the slower resolution of γH2AX, TFP-co-treated cells initially exhibited even higher CFSE fluorescence than bleomycin-treated cells, indicating a more prolonged checkpoint response during the first 24 h post-treatment.
In contrast, the G1 fraction of doxorubicin-treated mESCs decreased dramatically from 20%to1%1%, whereas its G2 fraction increased from 11%to99%9%, indicating a lack of G1 checkpoint in mouse PSCs and accumulation of cells at the G2 checkpoint.
Similarly, the mrc1-N5 allele generated through a partial N-terminal deletion interacts synthetically with rad9 deletion, indicating a role in the checkpoint response [ 37].
Finally, pol2 18, which has a mutation in the N-terminal catalytic domain pro710Ser, is synthetic lethal with rad9Δ, indicating a role in the checkpoint response [ 32].
Although we detected a marginal increase of p53 protein levels in SINEG2 keratinocytes, its direct transcriptional target p21WAF1/CIP1 was significantly downregulated, indicating a defective G1 'tetraploidy checkpoint' in GLI2ΔN-expressing GLI2ΔN-expressing
Quantification of 4N cells with phosphorylated Histone H3 revealed that mitotic U251-NG2 and U251-NG2 ctrl shRNA cells were diminished after IR compared to the U251 cells, indicating a more efficient G2 checkpoint in the NG2 positive population.
The PTX-induced endoreduplication is associated in Myc overexpressing cells with a reduced expression of MAD2, essential component of the molecular core of the spindle assembly checkpoint (SAC), indicating an impairment of this checkpoint.
