Table 1.

Summary of RASM cell-derived mitogen purification

Purification step	Protein recovered, μg	Total activity, units*	Specific activity, units/μg	Activity recovered, %	Purification factor
Conditioned medium	14,250†	2490	0.139	100	—
High Q anion exchange	2,464†	960	0.39	39	3
Superdex-75	2.3‡	144	63	5.8	453
C4 HPLC	0.024§	5.7¶	238	0.23	1,712

^*One unit of activity is defined as the amount of sample required to stimulate [³H]thymidine incorporation to a level 50% of that observed for serum in Swiss 3T3 cells. 

^†Determined by protein assay kit (Bio-Rad). 

^‡Estimated by silver staining of SDS/PAGE-resolved protein. 

^§Blotted protein band determined by amino acid composition. 

^¶Activity attenuated by low-pH conditions.