Protein concentration is too low (Protein Extraction)

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Nanodrop reads A280 ≈ 0.09, concentration ≈ 0.05 mg/mL; SDS-PAGE shows very faint overall bands; BCA quantification confirms low yield. Common causes: 1) Tissue / cell input was insufficient 2) Lysis was incomplete — protein not released 3) Lysis buffer volume or ratio was wrong 4) Protein loss during centrifugation/transfer 5) Target protein has intrinsically low expression Solutions: 1) Increase sample input 2) Lyse thoroughly on ice (vortex, sonication, or repeated pipetting) 3) Optimize lysis-buffer volume relative to sample mass (e.g. increase RIPA volume) 4) Optimize centrifugation conditions to avoid pellet sticking 5) For low-abundance targets, enrich (IP, affinity capture) or use a more sensitive detection method