SERPINB2 and neoplasm: According to our findings in experiments 3 and 4, a single systemic (i.p.)injection of 213Bi-PAI2 at doses of 3 and 6 mCi kg−1 during the growth of tumours, when the tumours were 35 mm3 (early stage) and 90 mm3 (late stage) in size, strongly regressed tumour progression for at least 5–7 weeks.