Before she learned she was Caroline, Glados would have NEVER defended Chell, having a deep hatred of her prior to learning she is her mom (sort of). Also, in the credits song, Glados says Chell is a lot like Caroline. She learns of Ratman erasing Glados’s memory.

Chell, documented as Test Subject #1 but previously as #1498, is the silent protagonist of Portal and the single-player campaign of Portal 2; she is a former Aperture Science Test Subject. Her predecessor is Mel.

Test Subject #1
Chell, documented as Test Subject #1 but previously as #1498, was a test subject of the Aperture Science computer-aided Enrichment Center, and was involved in the testing of the Company’s Handheld Portal Device (commonly known as the Portal Gun).

There were other test subjects alive but most if not all died between the events of portal and portal 2. This is because they were other test subjects in the relaxation vault but died after being in suspended animation for too long which is stated by Wheatly.

Fourth, it perfectly reflects the love/hate relationship that GLaDOS feels towards Chell. There are so many lines throughout both games where GLaDOS lets a little sentimentalism leak out, then turns around to slam Chell, or where she basically says that it’s good to have Chell around to test her.

It is revealed that GLaDOS had murdered everyone in the facility using deadly neurotoxin.

Known Test Subjects

• Al Anderson.
• ATLAS and P-body (robotic)
• Arsenio Navarro.
• Brenda Bogenschutz.
• Charles Cardoze.
• Chell (human)
• Christopher M. Pham.
• David C. Self.

She also has brain damage, which explains why she cannot talk in the second game. In the events of the second game, Glados discovers she is Caroline (basically) and that Chell was her daughter. She becomes more protective and loving torwards Chell. At the end of the game, she says that she deletes Caroline.

Cave Johnson was Chell’s father, and Caroline, her mother (if you translate the turret song at the end of the game, and consider what GLaDOS said about Caroline, it shows that GLaDOS still had a little of Caroline inside her, before Caroline’s deletion).

The presence of EN2 in urine was highly predictive of PC, with a sensitivity of 66% and a specificity of 88.2%, without requirement for DRE. There was no correlation with PSA levels.

Different mutations in the mouse homologs, En1 and En2, produced different developmental defects that frequently are lethal. The human engrailed homologs 1 and 2 encode homeodomain-containing proteins and have been implicated in the control of pattern formation during development of the central nervous system.

A method for diagnosing prostate cancer by detection of EN2 in urine has been developed. The results of a clinical trial of 288 men suggest that EN2 could be a marker for prostate cancer which might prove more reliable than current methods that use prostate-specific antigen (PSA).

En2 transcription factor is involved in patterning the midbrain of the central nervous system during embryonic development. Specifically, it is required for proper positioning of folia in the developing hemispheres.