Figure 5.

The functional effects of MST4 are dependent on its kinase domain. A, Structure of wild-type and MST4 mutants. B, MST4 wild-type and mutants (K53E, T178A, and δC) were stably overexpressed in LβT2 pituitary cells, and mRNA levels were detected by semiquantitative PCR. C, The MST4 kinase sequence modulates MST4-induced protective effects against cell death. Hypoxia-induced apoptosis (1% O₂ for 17 h) was measured by TUNEL staining in LβT2 transfectants. Rates of apoptosis were expressed as percentage of TUNEL-positive cells to total cells (n = 4). *, P < .001, MST4 wild-type and δC compared with vector control; #, P < .01, MST4 mutants of K53E and T178A compared with wild type.