Use of a kit for diagnosing the presence or absence of Alzheimer's Disease in a subject, the kit comprising: a) an agent that is a protein kinase C activator chosen from bradykinin; α-APP modulator; bryostatin; bryologues; bombesin; cholecystokinin; thrombin; prostaglandin F2α; vasopressin; 6-[N-decylamino]-4-hydroxymethylinole; 1,2-Dioctanoyl-sn-glycerol; farnesylthiotriazole; Gnidimacrin, Stellera chamaejasme L.; (-)-Indolactam V; Lipoxin A 4; Lyngbyatoxin A, Micromonospora sp.; Oleic acid; 1-Oleoyl-2-acetyl-sn-glycerol; 4α-Phorbol-12,13-didecanoate; L-α-Phosphatidylinositol-3,4-bisphosphate, Dipalmitoyl-, Pentaammonium Salt; L-α-Phosphatidylinositol-4,5-bisphosphate, Dipalmitoyl-, Pentaammonium Salt; L-α-Phosphatidylinositol-3,4,5-trisphosphate, Dipalmitoyl-, Heptaammonium Salt; 1-Stearoyl-2-arachidonoyl-sn-glycerol; Thymeleatoxin, Thymelea hirsuta L.; insulin; lysophosphatidylcholine; lipopolysaccharide; daunorubicin; and vanadyl sulfate; b) an antibody specific for a phosphorylated first MAP kinase protein, wherein the first MAP kinase protein is Erk1; c) an antibody specific for a phosphorylated second MAP kinase protein, wherein the second MAP kinase protein is Erk2; wherein the use comprises: i) contacting cells from said subject with said agent that is a protein kinase C activator; ii) measuring the ratio of said phosphorylated first MAP kinase protein to said phosphorylated second MAP kinase protein, wherein said phosphorylated first and second MAP kinase proteins are obtained from said cells after said contacting step; iii) measuring the ratio of said phosphorylated first MAP kinase protein to said phosphorylated second MAP kinase protein in cells from said subject that have not been contacted with the agent of step (i); iv) subtracting the ratio obtained in step (iii) from the ratio obtained in step (ii); and v) diagnosing the presence of Alzheimer's Disease in said subject based on the difference calculated in step (iv). a) an agent that is a protein kinase C activator chosen from bradykinin; α-APP modulator; bryostatin; bryologues; bombesin; cholecystokinin; thrombin; prostaglandin F2α; vasopressin; 6-[N-decylamino]-4-hydroxymethylinole; 1,2-Dioctanoyl-sn-glycerol; farnesylthiotriazole; Gnidimacrin, Stellera chamaejasme L.; (-)-Indolactam V; Lipoxin A 4; Lyngbyatoxin A, Micromonospora sp.; Oleic acid; 1-Oleoyl-2-acetyl-sn-glycerol; 4α-Phorbol-12,13-didecanoate; L-α-Phosphatidylinositol-3,4-bisphosphate, Dipalmitoyl-, Pentaammonium Salt; L-α-Phosphatidylinositol-4,5-bisphosphate, Dipalmitoyl-, Pentaammonium Salt; L-α-Phosphatidylinositol-3,4,5-trisphosphate, Dipalmitoyl-, Heptaammonium Salt; 1-Stearoyl-2-arachidonoyl-sn-glycerol; Thymeleatoxin, Thymelea hirsuta L.; insulin; lysophosphatidylcholine; lipopolysaccharide; daunorubicin; and vanadyl sulfate; b) an antibody specific for a phosphorylated first MAP kinase protein, wherein the first MAP kinase protein is Erk1; c) an antibody specific for a phosphorylated second MAP kinase protein, wherein the second MAP kinase protein is Erk2; i) contacting cells from said subject with said agent that is a protein kinase C activator; ii) measuring the ratio of said phosphorylated first MAP kinase protein to said phosphorylated second MAP kinase protein, wherein said phosphorylated first and second MAP kinase proteins are obtained from said cells after said contacting step; iii) measuring the ratio of said phosphorylated first MAP kinase protein to said phosphorylated second MAP kinase protein in cells from said subject that have not been contacted with the agent of step (i); iv) subtracting the ratio obtained in step (iii) from the ratio obtained in step (ii); and v) diagnosing the presence of Alzheimer's Disease in said subject based on the difference calculated in step (iv).