RTX resistance and ΔCD20 protein expression. (A) CDC lysis assay reporting the percentage of lysis of in vitro RTX-resistant established B cells plotted against an increasing dose of RTX. Both experiments (decrease of CD20 mean fluorescence intensity [MFI] and decrease of percentage of cell lysis) favored RTX-resistance establishment after repeated RTX exposure. Error bars indicate SE of 3 experiments. (B) Representative (of 3 experiments) Western blot (WB) analysis, using the c-Term anti-CD20 (recognizing wt and truncated CD20 proteins) on whole lysates from RTX-resistant B-cell lines. Antiactin WBs on the whole-cell lysates were performed as controls. Dashed boxes highlight an increase of immunoreactive signal generated by ΔCD20 protein. (C) Quantification of the WB immunoreactive ΔCD20 signal with the BIO-1D advanced software and normalized with actin signal. Results are reported as the protein ratio of ΔCD20/wtCD20 (left). RT-qPCR quantification of ΔCD20 transcripts expressed as follows: relative percentage of ΔCD20 = (ΔCD20 / wtCD20 + ΔCD20) × 100. Mean of triplicate is reported (right panel).