Question: In 30 Rock, why are Jenna and Tracy consistently in fear of losing their spotlight?
About the article "30 Rock", section "Season 4".

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The fourth season of "30 Rock" premiered on October 15, 2009.
Like the previous season 3, it also consisted of 22 episodes.
A recurring story arc early in the season revolved around Jack's request that Liz cast a new actor for "TGS", and Liz's subsequent search for the perfect comedian, much to the dismay of Jenna and Tracy, who fear losing their spotlight.
The later half of the season focused on two complementary story arcs: Jack's inability to choose between his two girlfriends, and Liz's inability to find a boyfriend to live up to her expectations and Jenna's relationship with a Jenna Maroney impersonator.
The season has also featured such guest stars as Julianne Moore, Jon Bon Jovi, Cheyenne Jackson, Sherri Shepherd, Will Forte, Elizabeth Banks, Michael Sheen, Matt Damon, and James Franco.
Liz and Jenna have known each other since 1993, when they met at an audition for a car dealership commercial in Chicago, although there are many other versions of how they met (At a bachelor party, at a play Jenna was in).
Liz stated in the pilot that she and Jenna worked for years to get "The Girlie Show", having formerly been roommates in a Chicago neighborhood called "Little Armenia" around 1996.
Given Jenna's insecure nature, Liz is generally forced to act as her rock.
This has caused Liz some annoyance, especially after Jack increased Jenna's stress level and paranoia by hiring Tracy Jordan and changing the show's name from "The Girlie Show" to "TGS With Tracy Jordan".
Liz has been seen complaining about Jenna's erratic tendencies behind her back, usually with Pete.
Jenna once got mad at Liz when she overheard Liz describe her to Tracy as being "paranoid" and "neurotic."
Jenna once slept with Liz's brother Mitch and said he was disgusting in bed.
Liz explains this by saying that Mitch has not been right since he was in some kind of skiing accident, because of which he thinks it's still 1985 and he's still a teenager.
Nonetheless, Jenna attempts to seduce Mitch once more in the episode "Ludachristmas.
"Despite their frustrations and occasional rivalries, however, the show often reveals that the two women appreciate their friendship and do their best to be supportive of the other's careers.
When the phrase "That's a deal breaker, ladies" is coined by Jenna thanks to Liz's writing, Jenna surrenders the spotlight with a surprisingly short sulking period.
She later encourages Liz to write a book and take on a talk show gig based on the catch phrase (though the talk show is very short-lived). 
"Grandmentor" is the of the sixth season of the American television comedy series "30 Rock", and the 116th overall episode of the series.
It was directed by Beth McCarthy-Miller, and written by Sam Means.
The episode originally aired on the National Broadcasting Company (NBC) network in the United States on March 22, 2012.
In the episode, Jack (Alec Baldwin) decides to create a TV-movie about Avery to keep her in the media spotlight.
Liz (Tina Fey) agrees to write the script, and Jenna (Jane Krakowski) campaigns to star in it.
Kenneth (Jack McBrayer) objects to new page Hazel's (Kristen Schaal) permissiveness with Tracy (Tracy Morgan), prompting Hazel to choose Liz as a mentor. 
Liz becomes furious when Jack decides that Tracy should be the number one priority on "The Girlie Show".
Jenna fears that Tracy will begin to overshadow her, but Tracy is quite pleased with his new job on the show.
Liz and Jenna become more aggravated when Jack decides to change the name of "The Girlie Show" to "TGS with Tracy Jordan", without consulting either of them.
Jack has Tracy and Jenna appear in a promotion for the show, in which Tracy angers Jenna by forgetting her name and by not letting her speak.
After the promotion, Liz tries to re-assure Jenna by telling her that nobody on the show likes Tracy and that the only reason that he is on the show is because of Jack.
Liz finds out that Jenna's microphone was still on, and everyone in the studio heard her say terrible things about Jack and Tracy.
Liz attempts to make amends by talking to Tracy during a rehearsal, during which she makes negative remarks about Jenna and the other members of her staff.
Liz is notified by Kenneth Parcell (Jack McBrayer) that her chat with Tracy was aired over the studio's monitors, which meant that everyone heard and saw her making the comments.
Liz's staff show their displeasure by throwing food and other objects at her.
Liz and Tracy discuss an idea to get everyone together to try and smooth things over, and Tracy decides to invite Liz and the staff to a party aboard a yacht.
Tracy gets along well with everyone at the party, including Jenna, and things appear to be going very well.
Liz soon discovers that the yacht does not belong to Tracy, and the yacht's real owner shows up with the NYPD.
The following day Liz learns that Jack paid the newspapers to keep Tracy out of the press but left a photo of Jenna passing out on the yacht in their pages, which Jenna sees as exciting and flattering. 
After their separation, Tracy and his wife Angie get back together on the condition that Tracy must never leave her sight.
Liz is surprised to find Tracy on time in his dressing room, although Angie confesses that she cannot take care of Tracy alone, and asks for Liz's help.
Angie leaves to take care of personal issues, trusting Liz to watch over him.
Busy with her own work, Liz forgets about her promise and Tracy leaves for a strip club.
When Angie returns, Liz lies about his whereabouts and tries to cover her mistake, however Angie realizes that Tracy has been to a strip club, and blames the situation on Liz.
Angie demands that all decisions regarding sketch ideas be run through her first, and rejects all of Liz's ideas.
To solve the problem, Liz offers Angie "consultant" credit, but she declines the offer.
Liz decides to fight Angie, but Tracy scolds the women for their immature behavior and he reconciles with Angie.
Jack hires Len to investigate his past when he learns that he is a possible candidate for the position of president at G.E.. Knowing that the company is looking for anything that could possibly embarrass them, Jack hires Len to find anything incriminating before the company does.
When Len discovers that Jack has a collection of cookie jars, he advises him to get rid of them.
Jack cannot bear to destroy his cookie jars, and when he realizes Kenneth has a similar enjoyment, he gives him the collection.
Jenna has become more famous after gaining weight, and sorts through large amounts of fan mail.
Jack congratulates her on her weight, and Jenna enjoys her new friendship with him.
While talking to Liz, Jenna begins to worry about losing weight, and fears her popularity will decline.
Upset that Jenna is losing weight, Jack sends Kenneth to follow her around and make sure she keeps her weight on.
Liz tells Kenneth to insult Jenna if he wants her to eat more, and writes down a list of things to say to Jenna to hurt her.
Jenna takes the insults as compliments, and tries to seduce Kenneth.