DESCRIPTION

FLI1 (Friend Leukemia Integration 1) is a proto-oncogene that encodes a member of the ETS (E-twenty-six) family of transcription factors. The FLI1 gene was initially identified as a common site of integration for the Friend murine leukemia virus, leading to erythroleukemia in mice. As a proto-oncogene, aberrant expression or activation of FLI1 can drive tumorigenesis. It is most famously implicated in Ewing's Sarcoma, a malignant bone and soft tissue tumor affecting children and young adults. Paradoxically, in certain contexts like some forms of T-cell acute lymphoblastic leukemia (T-ALL) and breast cancer, FLI1 can act as a tumor suppressor, where its loss or downregulation promotes cancer progression. This highlights the context-dependent nature of FLI1's function.

PRINCIPLE OF THE ASSAY

Sandwich ELISA structure (Detection antibody labeled with HRP) A capture antibody is pre-coated onto the bottom of wells which binds to analyte of interest. A detection antibody labeled with HRP also binds to the analyte. TMB acts as the HRP substrate and the solution color will change from colorless to blue. A stop solution containing sulfuric acid turns solution yellow. The color intensity is proportional to the quantity of bound protein which is measurable at 450 nm with the correction wavelength set at 630 nm.

PRECISION

Intra-assay Precision (Precision within an assay) Three samples of known concentration were tested 8 times on one plate to assess intra-assay precision. Inter-assay Precision (Precision between assays) Three samples of known concentration were tested in 16 separate assays to assess inter-assay precision.

Intra-assay Precision

Sample	n	Mean (ng/mL)	SD	CV%
1	8	5.23	0.22	4.21
2	8	1.25	0.06	4.80
3	8	0.64	0.03	4.69

Inter-assay Precision

Sample	n	Mean (ng/mL)	SD	CV%
1	16	5.03	0.32	6.36
2	16	1.19	0.10	8.40
3	16	0.60	0.05	8.33

RECOVERY

The recovery of human/mouse FLI1 spiked to three different levels throughout the range of the assay in cell lysate was evaluated.

Sample Type		Average% of Expected	Range (%)
Cell lysate	1:32	88	83-91

LINEARITY

To assess the linearity of the assay, samples were diluted with the appropriate Sample Diluent to produce samples with values within the dynamic range of the assay. (The cell lysate was initially diluted 1:8.)

		Cell lysate
1:2	Average% of Expected	100
	Range (%)	-
1:4	Average% of Expected	114
	Range (%)	108-119
1:8	Average% of Expected	111
	Range (%)	110-112
1:16	Average% of Expected	110
	Range (%)	110-111

CALIBRATION

This immunoassay is calibrated against a highly purified recombinant human Human/Mouse FLI1 Sandwich ELISA Kit produced at Sunlong Medical™.