No.  The MTT assay is for living cells, not proteins. 

It can be counterintuitively difficult to assay pichia clones for expression.  Running gels might not be good enough, because they might not make enough of it to see with a generic stain.  You'll want some sort of immunoassay.  You need an antibody against your protein, or its tag if it has one.  If you have that, look at methods like Dot Blot, ELISA, Western... 

Sorry Hussein is not clear to me why you would like to perform MTT assay in the cells of pichia pastoris?

Do you would like to check if methanol induction decrease cell viability?