gene; genetic factor; genetic element
coagulation factor; clotting factor
macrophage migration inhibitory factor; MMIF
lethal factor; lethal gene
natural moisturizing factor; NMF
zero divisor; null factor; nil factor
zero divisor; null factor; nil factor
tumor necrosis factor (e.g. cachexin); tumour necrosis factor; TNF
tissue plasminogen activator; tPA; PLAT