Stability of endogenous or transfected VRK1 protein.

<p>(A) The variation in levels of endogenous VRK1 and p53 proteins in HeLa cells was followed at different time points after addition of cycloheximide. The p53 protein drops in less than 30 minutes as expected, but there is no detectable change in VRK1 protein even after twelve hours suggesting it has a very high stability. (B). HEK293T cells were transfected with plasmids expressing wild-type human VRK1 or its kinase-dead K179E mutant. The stability of both proteins was followed at different time points after cycloheximide addition. Cells were transfected with plasmids pCEFL-HA-VRK1 or pCEFL-HA-VRK1(K179E) as previously described (Vega et al., 2004). These experiments were independently performed three times.