sentences:  In scientific research, western blots for CA (24 kDa) can indicate a maturation defect by the high relative presence of a 25 kDa band (uncleaved CA-SP1).SP1 plays a critical role in HIV particle assembly, although the exact nature of its role and the physiological relevance of SP1 structural dynamics are unknown.The HIV nucleocapsid protein (NC) is a 7 kDa zinc finger protein in the Gag polyprotein and which, after viral maturation, forms the viral nucleocapsid.