Relationship between cell adhesion ability and lenalidomide resistance. (A) Illustration of the coculture experiment setup. The resistant cells were seeded in the upper chamber, and the parental cells were seeded in the lower chamber. After 1 week of coculture, the numbers of adherent and nonadherent cells were determined. After cell counting, cells were reseeded into a new 96-well plate to measure lenalidomide sensitivity. (B) Cell viability assay of cocultured cells with Cell Counting Kit-8. The values were normalized to those of the negative control. Parental cells (KMS21, KMS27, and KMS34) were cocultured with KMS34R cells. (C) Representative images of KMS21 and KMS27 cells after coculture with lenalidomide-resistant cells. Bars represent 50 μm. (D) Fraction of cells from each sample after coculture (left). Total cell numbers in each sample (right). (E) Illustration of the cell adhesion experiment setup with ultra-low attachment plates. Each lenalidomide-resistant cell line was seeded at 5000 cells per well, and after 96 hours, cell proliferation was measured with a cell viability assay. (F) Cell viability assay of KMS21R, KMS27R, and KMS34R cells using ultra-low attachment plates. The values were normalized to those of the negative control. The error bars indicate standard deviation values. *P < .05.