Abstract: The present invention relates to kits and methods for performing dual-staining immunohistochemistry (IHC) for the detection of specific cell populations in tissue samples containing heterogeneous populations of cells, which can be observed by a light microscope for co-localization of distinct pigments. The method includes providing a tissue sample comprising fixed cells; exposing the sample to first and second ligands that recognize different marker proteins found at the same cellular location, thereby forming a ligand-labeled sample; exposing the ligand-labeled sample to first and second labeling reagents, the first labeling reagent binding to the first ligand and the second labeling reagent binding to the second ligand, the first and second labeling reagents each forming distinct pigments; and identifying the number of cells that display only one particular pigment, or more than one pigment, by the different coloration of the cellular location labeled by the distinct pigment.

Abstract: The present invention relates to a method of determining the presence of a retinoblastoma protein (Rb)-mediated cancerous or pre-cancerous condition in a sample of fixed cells that involves exposing the sample to an antibody that recognizes phosphorylation of serine on the retinoblastoma protein (pS-Rb), and identifying cells in the sample that are recognized by the antibody to pS-Rb, where the recognition of pS-Rb in the sample determines the presence of an Rb-mediated cancerous or pre-cancerous condition. The method also involves identifying the presence of specific cell cycle markers and positive and negative cell cycle regulators to assess the stage of disease progression in a cancer patient having an (Rb)-mediated cancer. The present invention also relates to methods of assessing the efficacy of cancer therapy for an Rb-mediated cancer, determining the mechanism of cell cycle progression in an Rb-mediated cancer, and identifying cells predisposed to developing an Rb-mediated cancerous condition.

Abstract: The present invention relates to kits and methods for performing dual-staining immunohistochemistry (IHC) for the detection of specific cell populations in tissue samples containing heterogeneous populations of cells, which can be observed by a light microscope for co-localization of distinct pigments. The method includes providing a tissue sample comprising fixed cells; exposing the sample to first and second ligands that recognize different marker proteins found at the same cellular location, thereby forming a ligand-labeled sample; exposing the ligand-labeled sample to first and second labeling reagents, the first labeling reagent binding to the first ligand and the second labeling reagent binding to the second ligand, the first and second labeling reagents each forming distinct pigments; and identifying the number of cells that display only one particular pigment, or more than one pigment, by the different coloration of the cellular location labeled by the distinct pigment.

Abstract: The present invention relates to a method of determining the presence of a retinoblastoma protein (Rb)-mediated cancerous or pre-cancerous condition in a sample of fixed cells that involves exposing the sample to an antibody that recognizes phosphorylation of serine on the retinoblastoma protein (pS-Rb), and identifying cells in the sample that are recognized by the antibody to pS-Rb, where the recognition of pS-Rb in the sample determines the presence of an Rb-mediated cancerous or pre-cancerous condition. The method also involves identifying the presence of specific cell cycle markers and positive and negative cell cycle regulators to assess the stage of disease progression in a cancer patient having an (Rb)-mediated cancer. The present invention also relates to methods of assessing the efficacy of cancer therapy for an Rb-mediated cancer, determining the mechanism of cell cycle progression in an Rb-mediated cancer, and identifying cells predisposed to developing an Rb-mediated cancerous condition.