Genotype -F-, ompT, hsdSB(rB-mB-), dcm, gal, tonA.BL21 competent cells are a general expression host for use with most promoter systems such as and D. + phenotype allows for robust growth. and T protease mutations minimize product degradation. Conveniently packaged as single use aliquots of 50 ?L in a microcentrifuge tube. Transformation procedures are performed directly in the microcentrifuge tube, eliminating the need to dispense. The single use format avoids freeze/thaw issues, or waste of excess cells. Each microcentrifuge tube is individually labeled with product name, catalog number, aliquot, and lot number. -F, T, S(r-m-), A. Efficiency - >1 x 107 transformants/?g pUC19 Storage Conditions - Store at -80?C.