The human CD20 coding sequence was inserted into the ROSA26 locus in EL4 cells. Human CD20 is highly expressed on the surface of B-hCD20 EL4 cells.

Gene targeting strategy for B-hCD20 EL4 cells. The exogenous promoter and human CD20 coding sequence were inserted into the ROSA26 locus in murin

CD20 expression analysis in B-hCD20 EL4 cells by flow cytometry. Single cell suspensions from wild-type EL4 and B-hCD20 EL4 cultures were stained with species-specific anti-CD20 antibody. Human CD20 was detected on the surface of B-hCD20 EL4 cells but not wild-type EL4 cells. The 2-E06 clone of B-hCD20 EL4 cells was used for in vivo experiments.

Subcutaneous homograft tumor growth of B-hCD20 EL4 cells. B-hCD20 EL4 cells (2x10⁵) and wild-type EL4 cells (2x10⁵) were subcutaneously implanted into C57BL/6N mice (female, 6-9-week-old, n=6). Tumor volume and body weight were measured twice a week. (A) Average tumor volume ± SEM. (B)  Body weight (Mean± SEM). Volume was expressed in mm³ using the formula: V=0.5 × long diameter × short diameter². As shown in panel A, B-hCD20 EL4 cells were able to establish tumors in vivo and can be used for efficacy studies.