Table 1. Expression of the hPOLISc or hPOLHSc in yeast is non-mutagenic.

Plasmid in yeast transformants	Rate of forward mutations to canavanine-resistance Canr×10−7 *
pESC-LEU	4.8
	(1.0–11)
pESC-TRP	4.1
	(2.8–7.5)
pESC-URA	3.6
	(1.7–6.1)
pESC-TRP-hPOLISc	10.6
	(3.7–14)
pRS424-GAL-GST-TRP- hPOLISc	4.8
	(1.5–8.9)
pESC-URA-hPOLHSc	2.7
	(1.3–12)
pESC-URA-hPOLHSc and pESC-TRP-hPOLISc	4.7
	(2.7–6.9)
pESC-pmCDA1	130
	(95–250)

* Median for 12-18 independent cultures. The 95% confidence limits are in parenthesis.