Finding Lower Case Data From Table

Hi,

My database is case insensitive. However, the application is case sensitive for the data in the table.

I need to find out the data from the table where the data is stored in lower case.

Here is the sample data:
Table: inv_manager
column: sku varchar(5)
Data: 1134X
1135x
1123a
b145Y

I just need query to return row 2, 3, 4.

Here is my query:

select sku from inv_manager where sku like lower('%[a-z]%')

The problem is it returns all the rows from the table including first one.

How can I return just the data with lower case ?

Thanks