Claims
- 1. A cell culture comprising methotrexate (MTX) sensitive recombinant host cells transformed with an expression vector comprising a first DNA sequence encoding a dihydrofolate reductase (DHFR) protein with a low binding affinity for MTX, and a second DNA sequence encoding human tissue plasminogen activator (tPA), tPA encoded by said second DNA sequence, and an effective amplifying concentration of MTX.
- 2. The cell culture of claim 1 wherein said recombinant host cells are CHO cells.
- 3. The cell culture of claim 2 wherein said CHO cells are of the cell line CHO-K1(ATCC No. CCL 61).
- 4. The cell culture of claim 1 wherein the MTX concentration is between 20 and 500,000 nM.
- 5. The cell culture of claim 4 wherein said concentration is at least 100 nM.
Parent Case Info
This is a continuation of application Ser. No. 08/450,874, filed May 26, 1995 now U.S. Pat. No. 5,849,574, which is a continuation of application Ser. No. 08/162,354, filed Dec. 3, 1993 now U.S. Pat. No. 5,424,198, which 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, U.S. Ser. No. 06/398,003, filed Jul. 14, 1982, and U.S. Ser. No. 06/483,052, filed Apr. 7, 1983.
US Referenced Citations (8)
Number |
Name |
Date |
Kind |
4766075 |
Goeddel et al. |
Aug 1988 |
|
4853330 |
Goeddel et al. |
Aug 1989 |
|
5010002 |
Levinson et al. |
Apr 1991 |
|
5011795 |
Levinson et al. |
Apr 1991 |
|
5246850 |
Bennett et al. |
Sep 1993 |
|
5268291 |
Levinson et al. |
Dec 1993 |
|
5346824 |
Anderson et al. |
Sep 1994 |
|
5616486 |
Anderson et al. |
Apr 1997 |
|
Continuations (5)
|
Number |
Date |
Country |
Parent |
08/450874 |
May 1995 |
US |
Child |
09/105412 |
|
US |
Parent |
08/162354 |
Dec 1993 |
US |
Child |
08/450874 |
|
US |
Parent |
07/499209 |
Mar 1990 |
US |
Child |
07/663103 |
|
US |
Parent |
07/149990 |
Jan 1988 |
US |
Child |
07/499209 |
|
US |
Parent |
06/459153 |
Jan 1983 |
US |
Child |
07/149990 |
|
US |