Protocol for phenotype-specific immunodetection of cyclins using 488/630 nm dual laser flow cytometry. This protocol is for use with the D and E cyclins and employs 488 nm argon laser excitation of propidium iodide and a FITC-conjugated phenotypic label, and 630 nm NeNe or diode laser excitation of the fluorochrome Cy5 to detect cell cycle-specific cyclin D expression.