Claims
- 1. A method of preparing t-PA in host cells which method comprises growing the host cells containing transfecting DNA encoding DHFR and t-PA under conditions such that said t-PA protein is produced in amounts of at least 0.1 pg of t-PA per cell per day.
- 2. A method according to claim 1 further comprising recovering said t-PA.
- 3. A method according to claim 1 wherein said host cells are mammalian cells.
- 4. A method according to claim 3 wherein said host cells are Chinese hamster ovary (CHO) cells.
- 5. A method according to claim 3 wherein said DHFR is wild type DHFR.
- 6. A method according to any one of claims 1, 2, 3, 4 or 5 wherein t-PA is produced in amounts of at least 20 .mu.g per cell per day.
- 7. A method according to claim 1 wherein the host cells are deficient in DHFR.
- 8. A method according to claim 7 wherein the host cells are sensitive to MTX.
Parent Case Info
This is a division of application Ser. No. 07/663,103, filed Feb. 28, 1991, now U.S. Pat. NO. 5,268,291 which is a continuation of application Ser. No. 07/499,209, filed Mar. 22, 1990, now U.S. Pat. No. 5,010,002, which is a continuation of application Ser. No. 07/149,990, filed Jan. 27, 1988, abandoned, which is a continuation of application Ser. No. 06/459,153, filed Jan. 19, 1983, abandoned. Reference is hereby made under 35 USC 120/121 to U.S. Ser. No. 06/374,860, filed May 5, 1982, now abandoned, U.S. Ser. No. 06/398,003, filed Jul. 14, 1982, now abandoned, and U.S. Ser. No. 06/483,052, filed Apr. 7, 1983 now U.S. Pat. No. 4,766,075.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
5010002 |
Levinson et al. |
Apr 1991 |
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5268291 |
Levinson et al. |
Dec 1993 |
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Divisions (1)
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Number |
Date |
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Parent |
663103 |
Feb 1991 |
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Continuations (3)
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Number |
Date |
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Parent |
499209 |
Mar 1990 |
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Parent |
149990 |
Jan 1988 |
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Parent |
459153 |
Jan 1983 |
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