Can I substitute LB (Luria-Bertoni) media for the LB-Lennox media recommended in the shRNA product manuals?

It is not recommended. In certain host cells, the salt concentration can make a difference in plasmid yields. The difference between LB and LB-Lennox is the amount of NaCl in each: LB contains: 10g/L NaCl LB-Lennox contains: 5.0g/L NaCl We grow all shRNA clones in LB-Lennox. Also, it is also important to note that manufacturers of zeocin (selection marker used in some of the shRNA vectors) recommend LB-Lennox (low salt): http://www.invitrogen.com/site/us/en/home/support/FAQ/Product-Support-FAQ-Result.html?p_faqid=1222