The RMCE cassette of the TI{CRIMIC.TG4.2}α-Est1CR60247-TG4.2 insertion has been replaced with a TI{FFL.2} cassette that is in gene-trap (GT) orientation relative to α-Est1. This is expected to truncate the α-Est1 protein and to result in the expression of a separate mCherry protein under the control of endogenous α-Est1 regulatory sequences.