Methods of inhibiting the growth of cells or inducing cell death by contacting the cells with or introducing into the cells a composition including a 5′ triphosphate, 2′ fluoro-modified pyrimidine non-linear single stranded RNA at least 17 nucleotides long with a least 3 base pairings or a 5′ triphosphate, 2′ fluoro-modified double stranded RNA at least 17 base pairs long in an amount effective to inhibit cell growth, induce cell death or induce cytokine production by the cells. The methods also include administration of the compositions to a subject. The subject may have a proliferative disorder or infectious disease and administration of the compositions provided herein may treat the disorder or disease.