Patients with disease progression on venetoclax show elevated ERK1/2 signaling. (A) Volcano plot showing differentially expressed genes between pre and postvenetoclax progression time points from RNA-seq data with adjusted P value < .05 and |log₂(FC)| > 1.0. (B) Enrichment plots obtained from gene set enrichment analysis, which was performed on a list of all genes from DEG analysis and ranked based on t statistics. (C) sIgM and CD19 staining was performed on PBMCs collected from patients (n = 5) at pre- and postprogression on venetoclax time points. Mean fluorescent intensity was measured on gated CD19⁺ cells. (D) Representative western blot image showing pERK and ERK for PBMC lysates from pre- and postvenetoclax progression time points for 2 patients, together with quantification of pERK:ERK ratio (n = 5).