Abstract: Method for RKIP protein and p-RKIP protein quantitative measuring in a biological sample, comprising the steps of; a) coacting to two distinct supports: a1) an antibody recognizing a first amino acid sequence present in p-RKIP and an antibody recognizing a first amino acid sequence present in RKIP; b) adding a blocking solution and the biological sample; d) adding, in the respective supports d1) an antibody recognizing a second amino acid sequence present in RKIP and d2) an antibody recognizing a second amino acid sequence present in RKIP protein, one of said first and second sequence containing the phosphorylation of serine 153, e) adding a marker f) measuring an optical property of the two samples and comparing it with a calibration curve.