Thanks Dr Frida:

yes I used RT-PCR. I used it to see the difference between colon cancer group and treated groups. Frida Gorreja

In addition, If you do ELIZA in supernatant of cells after treatment the cells with some toxic reagent, than we are talking protein expression, higher reading causing apoptosis of cells. mRNA is first step of apoptosis, of course,

No, this only means increased mRNA expression of casüpase-3. Further information which would be necessary would be:

a) what's up with caspace-3 protein expression (translation, WB or ELISA)?

b) is caspase-3 activity (cleavage) increased in your cells (WB, or functional assay)

etc.