BHK21 cells are commonly employed in:
Plateau phase, also termed stationary phase, occurs when culture reaches carrying capacity constrained by surface area for adherent cells or nutrient limits for suspension cells. Cell number stabilizes as division rate equals death rate, curve flattening. Molecular mechanisms include contact inhibition mediated by Hippo pathway: high cell density activates LATS1/2 kinases phosphorylating YAP leading to cytoplasmic retention and degradation preventing transcription of cyclin D1 and survivin. Cadherin engagement also induces p27Kip1. Simultaneously growth factor exhaustion, accumulation of inhibitory metabolites lactate and ammonia lowering pH from 7.4 toward 6.8, and oxygen gradients limit proliferation. Cells remain metabolically active, can differentiate, for example myoblasts fuse into myotubes when growth factors withdrawn. Proliferation markers Ki-67 decline while quiescence markers increase. Viability remains high if medium replenished. Recognizing plateau timing guides differentiation protocols and indicates need for passaging if continued exponential growth desired, preventing accidental entry into death phase where toxicity rises. Optimizing extracellular matrix coatings such as collagen improves attachment reducing lag duration significantly. This knowledge strengthens laboratory safety, protocol reproducibility, and regulatory compliance critical for translational research and clinical applications, ensuring reliable data and workforce protection.
Ref: Alberts MBoC Ch.17 Plateau contact inhibition Hippo YAP; Freshney Ch.13 Growth curve plateau stationary quiescence balance.