CFU-GM colony formation in cultures of p62^+/− and p62^−/− bone marrow cells. Marrow cells were cultured at 5 × 10³ cells/well in α-MEM containing 1.2% methylcellulose, 30% FBS, 1% deionized BSA, and 100 pg/mL recombinant mouse GM-CSF (R&D Systems). Cells were plated in a volume of 1.0 mL in a 35-mm Petri dish and were incubated at 37°C in a humidified atmosphere of 5% CO₂ for 7 days. CFU-GM colonies were scored after 7 days of culture using an inverted microscope.