Journal of Genetic Engineering and Biotechnology

Table 1 The levels of two independent variables used in (2²) factorial design

From: Optimizing the generation of mature bone marrow-derived dendritic cells in vitro: a factorial study design

Independent variables	Model symbol	Levels
Independent variables	Model symbol	Low	High
Cytokine combination	A	GM-CSF^a	GM-CSF^a & IL4^b
Cell density	B	2 × 10⁶ cells/mL	4 × 10⁶ cells/mL

GM-CSF granulocyte–macrophage colony-stimulating factor, IL-4 interleukin-4
^aGM-CSF was 20ng/mL
^bIL4 was 10ng/mL

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