( ( ( ( Keratinocytes , ) ( which ( are ( produced ( at ( ( the ( bottom layer ) ) ( of ( the epidermis ) ) ) ) ) ) ) ) , ) ( ( are ( the ( main ( epidermal cells ) ) ) ) . ) )
(ROOT (S (NP (NP (NNS Keratinocytes)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBP are) (VP (VBN produced) (PP (IN at) (NP (NP (DT the) (JJ bottom) (NN layer)) (PP (IN of) (NP (DT the) (NNS epidermis))))))))) (, ,)) (VP (VBP are) (NP (DT the) (JJ main) (JJ epidermal) (NNS cells))) (. .)))
Keratinocytes, which are produced at the bottom layer of the epidermis, are the main epidermal cells.
(ROOT (S (NP (NNS Melanocytes)) (VP (VBP are) (VP (VBN located) (PP (IN in) (NP (NP (DT the) (JJ bottom) (NN layer)) (PP (IN of) (NP (DT the) (NNS epidermis))))))) (. .)))