Here, we found that the expression levels of the protein tyrosine
phosphatases (Ptpn11 and Ptprk) were upregulated under
HS. The MAPK pathway is activated by HS and hypo-osmotic stress
(Kamada et al., 1995; Yu and Huang, 2004). Protein phosphatases
play a crucial role in the MAPK pathway. Overexpression/deletion
of PTPs that inactivate the stress-activated MAPK results in cell
cycle disruption. PTPs might be important for preventing cross talk
between these pathways. Indeed, deletion of PTPs led to cross talk
between the cell wall integrity MEK and the MAPK Hog1, indicating
that PTPs are important for blocking signaling between
MAPK pathways (Winkler et al., 2002). Rapid temperature increases
up to 46 °C could induce high tyrosine phosphorylation/
activation in vitro (Yang et al., 1997). In our study upregulation of
the tyrosine phosphatase induced by HS indicated that, this protein
might be actively participated in the phosphorylation and
MAPK pathways.