Genomic editing of the S1PR2 locus provides a growth advantage to DLBCL cell lines in vitro and in vivo. The DLBCL cell lines (A) RC-K8 and (B) SU-DHL-6 were subjected to S1PR2 inactivation using CRISPR/Cas9 editing. Absolute cell counts of 2 to 3 independent clones derived from FACS single cells of the indicated genotypes were compared under standard cell culture conditions over 10 days without medium change. Pooled results from (A) 2 of a total of 4 independent experiments and (B) of 4 independent experiments are shown. P values were calculated using the Student t test on the average value for each genotype pooling S1PR2^+/− and S1PR2^−/− clones. (C-E) Ten million cells each of 5 S1PR2^+/+ clones (red), 4 S1PR2^+/− clones (light blue), and 2 S1PR2^−/− clones (all in the RC-K8 cell line; blue) were injected subcutaneously into the flanks of NSG mice. (C) Tumors were excised, representative macroscopic images were taken, and (D) tumor weights and (E) volumes were determined at the study end point 40 days post injection. Every dot represents 1 tumor, and plots show pooled data from 2 independent experiments. (F-H) Ten million cells per mouse of 2 to 3 replicates each of 3 independent S1PR2^+/+ clones (red) and 3 S1PR2^−/− clones (all in the SU-DHL-6 cell line; blue) were injected IV into MISTRG mice. Mice were euthanized 35 days after tumor cell injection, (F) their spleens were weighed, and the frequencies of hCD45⁺ cells in the (G) spleen and (H) bone marrow was determined by flow cytometry. Every dot represents 1 mouse; graphs represent pooled data from 2 independent experiments. (D-H) Horizontal lines indicate medians; P values were calculated using the Mann-Whitney U test. *P < .05; **P < .01; ***P < .001.